DEV Community: kaggle_study

[Android Studio|Kotlin] View

kaggle_study — Sun, 27 Feb 2022 06:20:09 +0000

basic Setting

    buildFeatures {
        viewBinding = true
    }

1) custom View
[MainActivity.kt]

class MainActivity : AppCompatActivity() {
    val binding by lazy {ActivityMainBinding.inflate(layoutInflater)}
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(binding.root)

        val customView = CustomView(this)
        binding.frameLayout.addView(customView)
    }
}

[CustomView.kt]

class CustomView(context: Context) : View(context) {
    override fun onDraw(canvas: Canvas?) {
        super.onDraw(canvas)

        val paint = Paint()
        paint.color = Color.BLACK
        paint.textSize = 100f

        canvas?.run {
            drawText("Hello", 0f, 100f, paint)
            customDrawCircle(canvas)
            customDrawRect(canvas)
        }
    }
    fun customDrawCircle(canvas:Canvas) {
        val paint = Paint()
        paint.style = Paint.Style.FILL
        paint.color = Color.BLUE

        canvas.drawCircle(150f, 300f, 100f, paint)
    }
    fun customDrawRect(canvas: Canvas) {
        val paint = Paint()
        paint.style = Paint.Style.STROKE
        paint.strokeWidth = 20f
        paint.color = Color.GREEN

        val rect = RectF(50f, 450f, 250f, 650f)
        canvas.drawRect(rect, paint)
    }
}

[activity_main.xml]

<androidx.constraintlayout.widget.ConstraintLayout
<TextView />
<FrameLayout />
</androidx.constraintlayout.widget.ConstraintLayout

2) custom Widget
[MainActivity.kt]

class MainActivity : AppCompatActivity() {
    val binding by lazy {ActivityMainBinding.inflate(layoutInflater)}
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(binding.root)
    }
}

[CustomText.kt]

class CustomText : AppCompatTextView {
    constructor(context: Context) : super(context) { }
    constructor(context: Context, attrs:AttributeSet) : super(context, attrs) {
        val attrList = context.obtainStyledAttributes(attrs, R.styleable.CustomText)
        for(i in 0 until attrList.indexCount) {
            val attr = attrList.getIndex(i)
            when(attr) {
                R.styleable.CustomText_delimeter -> {
                    attrList.getString(attr)?.let {
                        process(it)
                    }
                }
            }
        }
    }
    constructor(context: Context, attrs:AttributeSet, defStyleAttr:Int) : super(context, attrs, defStyleAttr ) {}
    fun process(delimeter: String) {
        if(text.length == 8) {
            val first4 = text.substring(0,4)
            val mid2 = text. substring(4,6)
            val last2 = text.substring(6)

            text = "$first4$delimeter$mid2$delimeter$last2"
        }
    }
}

[res > values > attrs.xml]

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <declare-styleable name="CustomText">
        <attr name="delimeter" format="string"/>
    </declare-styleable>
</resources>

[activity_mains.xml]

<androidx.constraintlayout.widget.ConstraintLayout
<com.example.myapplication.CustomText
 android:layout_width="wrap_content"
 android:layout_height="wrap_content"
 android:text="20220226"
 app:delimeter="-"/>
</androidx.constraintlayout.widget.ConstraintLayout

3-1) ViewPager & TabLayout
[MainActivity.kt]

class MainActivity : AppCompatActivity() {
    val binding by lazy {ActivityMainBinding.inflate(layoutInflater)}
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(binding.root)

        val list = listOf(FragmentA(), FragmentB(), FragmentC(), FragmentD() )
        // create adapter
        val pagerAdapter = FragmentPagerAdapter(list, this)
        // connect adapter and viewpager
        binding.viewPager.adapter = pagerAdapter

        // Create a list of titles as many as the number of tab menus
        val titles = listOf("A", "B", "C", "D")
        // connect TabLayout ViewPager2
        TabLayoutMediator(binding.tabLayout, binding.viewPager) { tab, position ->
            tab.text = titles.get(position)
        }.attach()
    }
}

class FragmentPagerAdapter(val fragmentList:List<Fragment>, fragmentActivity: FragmentActivity)
    : FragmentStateAdapter(fragmentActivity) {
    override fun getItemCount() = fragmentList.size
    override fun createFragment(position: Int) = fragmentList.get(position)
}

create [FragmentA.kt], [FragmentB.kt], [FragmentC.kt], [FragmentD.kt]
create with ([fragment_a.xml], [fragment_b.xml], [fragment_c.xml], [fragment_d.xml],)
[activity_main.kt]

<androidx.constraintlayout.widget.ConstraintLayout 
<androidx.viewpager2.widget.ViewPager2 android:id="@+id/viewPager"
<com.google.android.material.tabs.TabLayout android:id="@+id/tabLayout"
<androidx.constraintlayout.widget.ConstraintLayout

4) tablayout, viewpager and recyclerview
[MainActivity.kt]

class MainActivity : AppCompatActivity() {
    val binding by lazy {ActivityMainBinding.inflate(layoutInflater)}
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(binding.root)

        val list = listOf("MON", "TUE", "WED","THR", "FRI","SAT","SUN")
        // create adapter
        val pagerAdapter = CustomPagerAdapter(list)
        // connect adapter and viewpager
        binding.viewPager.adapter = pagerAdapter
        //Create a list of tab titles - skip
        // connect tablayout and viewpager
        TabLayoutMediator(binding.tabLayout, binding.viewPager) { tab, position ->
            tab.text = list.get(position)
        }.attach()
    }
}
class CustomPagerAdapter(val textList:List<String>) : RecyclerView.Adapter<CustomPagerAdapter.Holder>() {
    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): Holder {
        val binding = ItemViewpagerBinding.inflate(LayoutInflater.from(parent.context), parent, false)
        return Holder(binding)
    }
    override fun getItemCount() = textList.size
    override fun onBindViewHolder(holder: Holder, position: Int) {
        holder.setItem(textList.get(position))
    }
    class Holder(val binding:ItemViewpagerBinding) : RecyclerView.ViewHolder(binding.root) {
        fun setItem(text:String) {
            binding.textView.text = text
        }
    }
}

[activity_main.xml]

<androidx.constraintlayout.widget.ConstraintLayout
<com.google.android.material.tabs.TabLayout android:id="@+id/tabLayout"
</com.google.android.material.tabs.TabLayout
<androidx.viewpager2.widget.ViewPager2 android:id="@+id/viewPager"
/>
</androidx.constraintlayout.widget.ConstraintLayout

[item_viewpager.xml]

<androidx.constraintlayout.widget.ConstraintLayout
<TextView android:id="@+id/textView"
</androidx.constraintlayout.widget.ConstraintLayout

5) tablayout, viewpager and recyclerview
[MainActivity.kt]

class MainActivity : AppCompatActivity() {
    val binding by lazy {ActivityMainBinding.inflate(layoutInflater)}
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(binding.root)

        val list = loadData()
        // create adapter
        val pagerAdapter = CustomPagerAdapter(list)
        // connect adapter and viewpager
        binding.viewPager.adapter = pagerAdapter
        //Create a list of tab titles
        val titles = listOf("MON", "TUE", "WED","THR", "FRI","SAT","SUN")
        // connect tablayout and viewpager
        TabLayoutMediator(binding.tabLayout, binding.viewPager) { tab, position ->
            tab.text = titles.get(position)
        }.attach()
    }
    fun loadData() : List<Page> {
        val pageList = mutableListOf<Page>()
        pageList.add(Page(1, "Cloudy"))
        pageList.add(Page(2, "Clear"))
        pageList.add(Page(3, "Cloud"))
        pageList.add(Page(4, "Rain"))
        pageList.add(Page(5, "Snow"))
        pageList.add(Page(6, "Typhoon"))
        pageList.add(Page(7, "Fog"))
        return pageList
    }
}
class CustomPagerAdapter(val pageList:List<Page>) : RecyclerView.Adapter<CustomPagerAdapter.Holder>() {
    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): Holder {
        val binding = ItemViewpagerBinding.inflate(LayoutInflater.from(parent.context), parent, false)
        return Holder(binding)
    }
    override fun getItemCount() = pageList.size
    override fun onBindViewHolder(holder: Holder, position: Int) {
        holder.setItem(pageList.get(position))
    }
    class Holder(val binding:ItemViewpagerBinding) : RecyclerView.ViewHolder(binding.root) {
        fun setItem(page:Page) {
            with(binding) {
                textDay.text = "${page.day} DAY"
                textWeather.text = page.weather
            }
        }
    }
}
data class Page(val day:Int, val weather:String)

[activity_main.xml]

<androidx.constraintlayout.widget.ConstraintLayout
<com.google.android.material.tabs.TabLayout android:id="@+id/tabLayout"
<androidx.viewpager2.widget.ViewPager2 android:id="@+id/viewPager"
</androidx.constraintlayout.widget.ConstraintLayout

[item_viewpager.xml]

<androidx.constraintlayout.widget.ConstraintLayout
<TextView android:id="@+id/textDay"
<TextView android:id="@+id/textWeather"
</androidx.constraintlayout.widget.ConstraintLayout

6) add tablayout,viewpager, recyclerView and retrofit

[app > manifests > AndroidManifest.xml ]

<uses-permission android:name="android.permission.INTERNET"/>

[Gradle Scripts > build.gradle]

dependencies {
    // fragment
    implementation "androidx.fragment:fragment-ktx:1.4.1"
    // retrofit
    implementation 'com.squareup.retrofit2:retrofit:2.9.0'
    implementation 'com.squareup.retrofit2:converter-gson:2.9.0'
}

[MainActivity.kt]

class MainActivity : AppCompatActivity() {
    val binding by lazy { ActivityMainBinding.inflate(layoutInflater)}
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(binding.root)

        // 1. load page data
        val list = listOf( FragmentA(), FragmentB(), FragmentC() )
        // 2. create adapter
        val pagerAdapter = FragmentPagerAdapter(list, this)
        // 3. connect adapter and viewpager
        binding.viewPager.adapter = pagerAdapter

        // Create a list of titles as many as the number of tab menus
        val titles = listOf("tabname1", "tabname2", "tabname3" )
        // connect TabLayout ViewPager2
        TabLayoutMediator(binding.tabLayout, binding.viewPager) { tab, position ->
            tab.text = titles.get(position)
        }.attach()
    }
}
class FragmentPagerAdapter(val fragmentList:List<Fragment>, fragmentActivity: FragmentActivity)
    : FragmentStateAdapter(fragmentActivity) {
    override fun getItemCount() = fragmentList.size
    override fun createFragment(position: Int) = fragmentList.get(position)
}

[ApiService.kt]

interface ApiService {
    @GET("/apptech")
    fun getPosts(): Call<MutableList<Apptech>>
}

[ServiceGenerator.kt]

object ServiceGenerator {
    private val client = OkHttpClient.Builder().build()
    private val retrofit = Retrofit.Builder()
        .baseUrl("https://****.herokuapp.com")
        .addConverterFactory(GsonConverterFactory.create())
        .client(client)
        .build()

    fun <T> buildService(service: Class<T>): T {
        return retrofit.create(service)
    }
}

[Apptech.kt]

data class Apptech(
    val apptech_brand: String? = null,
    val apptech_title: String? = null,
    val apptech_period: String? = null,
    val apptech_point: Int? = null,
    val apptech_time: String? = null,
    val apptech_url: String? = null
)

[ApptechAdapter.kt]

class ApptechAdapter(val apptechData: MutableList<Apptech>) : RecyclerView.Adapter<ApptechAdapter.Holder>() {
    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): Holder {
        val binding = FragmentBItemBinding.inflate(LayoutInflater.from(parent.context), parent, false)
        return Holder(binding)
    }
    override fun getItemCount() = apptechData.size
    override fun onBindViewHolder(holder: Holder, position: Int) {
        //val apptech = apptechData.get(position)
        //holder.setApptech(apptech)
        return holder.setApptech(apptechData[position])
    }
    class Holder(val binding: FragmentBItemBinding) : RecyclerView.ViewHolder(binding.root) {
        fun setApptech(apptech: Apptech) {
            with(binding) {
                tvTitle.text = "${apptech.apptech_brand}"
                tvBody.text = "${apptech.apptech_title}"
                tvTime.text = "${apptech.apptech_time}"

                binding.root.setOnClickListener {
                    var url = "${apptech.apptech_url}"
                    val intent = Intent(Intent.ACTION_VIEW, Uri.parse(url))
                    ContextCompat.startActivity(itemView.context, intent, null)
                }
            }
        }
    }
}

[FragmentA.kt]

class FragmentA : Fragment() {
    override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        // Inflate the layout for this fragment
        return inflater.inflate(R.layout.fragment_a, container, false)
    }
}

[FragmentB.kt]

class FragmentB : Fragment() {
    lateinit var binding: FragmentBBinding
    override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        binding = FragmentBBinding.inflate(inflater, container, false)
        return binding.root
    }
    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)

        val serviceGenerator = ServiceGenerator.buildService(ApiService::class.java)
        val call = serviceGenerator.getPosts()
        call.enqueue(object : Callback<MutableList<Apptech>> {
            override fun onResponse(call: Call<MutableList<Apptech>>, response: Response<MutableList<Apptech>>) {
                with(binding){
                    recyclerView.apply{
                        adapter = ApptechAdapter(response.body()!!)
                        layoutManager = LinearLayoutManager(activity)
                    }
                }
            }
            override fun onFailure(call: Call<MutableList<Apptech>>, t: Throwable) {
                t.printStackTrace()
                Log.e("error", t.message.toString())
            }
        })
    }
}

[FragmentC.kt]

class FragmentC : Fragment() {
    override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? { 
        return inflater.inflate(R.layout.fragment_c, container, false)
    }
}

[activity_main.xml]

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <com.google.android.material.tabs.TabLayout
        android:id="@+id/tabLayout"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent">

        <com.google.android.material.tabs.TabItem
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Monday" />

        <com.google.android.material.tabs.TabItem
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Tuesday" />

        <com.google.android.material.tabs.TabItem
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Wednesday" />
    </com.google.android.material.tabs.TabLayout>

    <androidx.viewpager2.widget.ViewPager2
        android:id="@+id/viewPager"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/tabLayout" />
</androidx.constraintlayout.widget.ConstraintLayout>

[fragment_a.xml]

<androidx.constraintlayout.widget.ConstraintLayout 
<\androidx.constraintlayout.widget.ConstraintLayout

[fragment_b.xml]

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".fragment.FragmentB">
    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/recyclerView"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />
</FrameLayout>

[fragment_b_item.xml]

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    xmlns:tools="http://schemas.android.com/tools"
    android:paddingTop="8dp"
    android:paddingBottom="8dp"
    android:paddingLeft="15dp"
    android:layout_marginTop="4dp"
    android:layout_marginBottom="4dp"
    android:layout_marginLeft="8dp"
    android:layout_marginRight="8dp"
    android:orientation="horizontal"
    android:background="@drawable/border_a">

    <TextView
        android:id="@+id/tvTitle"
        tools:text="Hello Title"
        android:layout_width="80dp"
        android:layout_height="match_parent"
        android:textColor="@color/black"
        android:textSize="20sp" />

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="vertical"
        android:paddingLeft="15dp"
        android:paddingRight="15dp" >

        <TextView
            android:id="@+id/tvBody"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:textSize="14sp"
            tools:text="Hello Body"
            android:textAlignment="center"/>

        <TextView
            android:id="@+id/tvTime"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:textSize="14sp"
            tools:text="Hello Time"
            android:textAlignment="center"/>
    </LinearLayout>
</LinearLayout>

[fragment_c.xml]

<FrameLayout
<\FrameLayout

[res > drawable > border_a.xml]

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android">
    <solid android:color="#FFD0D0"></solid>
    <stroke android:width="3dp" android:color="#FF8484"/>
    <corners android:radius="15dp"/>
</shape>

[Android Studio|Kotlin] Containers, Create a list

kaggle_study — Sun, 27 Feb 2022 00:49:25 +0000

1) spinner

[MainActivity.kt]

class MainActivity : AppCompatActivity() {
    val binding by lazy { ActivityMainBinding.inflate(layoutInflater) }
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(binding.root)

        var data = listOf("-do choice", "1","2","3","4","5","6","7","8")
        var adapter = ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, data)
        with(binding) {
            spinner.adapter = adapter
            spinner.onItemSelectedListener = object : AdapterView.OnItemSelectedListener {
                override fun onNothingSelected(p0: AdapterView<*>?) {
                }
                override fun onItemSelected(p0: AdapterView<*>?, p1: View?, p2: Int, p3: Long) {
                    result.text = data.get(p2)
                }
            }
        }
    }
}

[activity_main.xml]

<TextView android:id="@+id/result"
<Spinner android:id="@+id/spinner"

2) RecyclerView
[MainActivity.kt]

class MainActivity : AppCompatActivity() {
    val binding by lazy { ActivityMainBinding.inflate(layoutInflater) }
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(binding.root)

        val data = loadMemoList()
        var adapter = CustomAdapter(data)
        binding.recyclerView.adapter = adapter
        binding.recyclerView.layoutManager = LinearLayoutManager(this)
    }


    fun loadMemoList(): MutableList<Memo> {
        val memoList = mutableListOf<Memo>()
        for (no in 0..100) {
            val title = "it is kotlin android ${no + 1}"
            val date = System.currentTimeMillis()
            var memo = Memo(no, title, date)
            memoList.add(memo)
        }
        return memoList;
    }
}

[activity_main.xml]

<androidx.constraintlayout.widget.ConstraintLayout
<androidx.recyclerview.widget.RecyclerView android:id="@+id/recyclerView"
<androidx.constraintlayout.widget.ConstraintLayout

[CustomAdapter.kt]

class CustomAdapter(var listData:MutableList<Memo>) : RecyclerView.Adapter<CustomAdapter.Holder>() {
    //var listData = mutableListOf<Memo>()
    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): Holder {
        val binding = ItemRecyclerBinding.inflate(LayoutInflater.from(parent.context), parent, false)
        return Holder(binding)
    }
    override fun getItemCount() = listData.size
    override fun onBindViewHolder(holder: Holder, position: Int) {
        val memo = listData.get(position)
        holder.setMemo(memo)
    }
    class Holder(val binding: ItemRecyclerBinding) : RecyclerView.ViewHolder(binding.root) {
        lateinit var currentMemo: Memo
        init {
            binding.root.setOnClickListener {
                Toast.makeText(binding.root.context, "clicked item : ${currentMemo.title}", Toast.LENGTH_SHORT).show()
            }
        }
        fun setMemo(memo: Memo) {
            currentMemo = memo
            with(binding) {
                textNo.text = "${memo.no}"
                textTitle.text = "memo.title"

                var sdf = SimpleDateFormat("yyyy/MM/dd")
                var formattedDate = sdf.format(memo.timestamp)
                textDate.text = formattedDate
            }
        }
    }
}

[item_recycler.xml]

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="50dp"
    android:gravity="center_vertical"
    android:orientation="horizontal">

    <TextView
        android:id="@+id/textNo"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_weight="1"
        android:text="01" />

    <TextView
        android:id="@+id/textTitle"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_weight="5"
        android:text="title" />

    <TextView
        android:id="@+id/textDate"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_weight="3"
        android:text="2020-01-01" />
</LinearLayout>

[Memo.kt]

data class Memo(
    var no: Int,
    var title: String,
    var timestamp:Long
    )

3) add Fragment to Activity
[MainActivity.kt]

class MainActivity : AppCompatActivity() {
    val binding by lazy { ActivityMainBinding.inflate(layoutInflater) }
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(binding.root)

        setFragment()
    }
    fun setFragment() {
        val listFragment: ListFragment = ListFragment()
        val transaction = supportFragmentManager.beginTransaction()
        transaction.add(R.id.frameLayout, listFragment)
        transaction.commit()
    }
}

[ListFragment.kt]

class ListFragment : Fragment() {
    override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? { 
        return inflater.inflate(R.layout.fragment_list, container, false)
    }
}

[activity_main.xml]

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:visibility="visible"
    tools:context=".MainActivity">

    <TextView
        android:id="@+id/textView2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="16dp"
        android:text="Activity"
        android:visibility="visible"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <androidx.fragment.app.FragmentContainerView
        android:id="@+id/frameLayout"
        android:name="com.example.myapplication.ListFragment"
        android:layout_width="0dp"
        android:layout_height="0dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/textView2"
        tools:layout="@layout/fragment_list" />

</androidx.constraintlayout.widget.ConstraintLayout>

[fragment_list.xml]

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".ListFragment">

    <TextView
        android:id="@+id/textView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/title_list"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <Button
        android:id="@+id/btnNext"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="24dp"
        android:text="NEXT"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.498"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/textView" />

</androidx.constraintlayout.widget.ConstraintLayout>

4) Fragment screen transition
[MainActivity.kt]

class MainActivity : AppCompatActivity() {
    val binding by lazy { ActivityMainBinding.inflate(layoutInflater) }
    val listFragment by lazy { ListFragment() }
    val detailFragment by lazy { DetailFragment() }

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(binding.root)

        setFragment()
    }
    fun setFragment() {
        val transaction = supportFragmentManager.beginTransaction()
        transaction.add(R.id.frameLayout, listFragment)
        transaction.commit()
    }

    fun goDetail() {
        val transaction = supportFragmentManager.beginTransaction()
        transaction.add(R.id.frameLayout, detailFragment)
        transaction.addToBackStack("detail")
        transaction.commit()
    }
    fun goBack() {
        onBackPressed()
    }
}

[ListFragment.kt]

class ListFragment : Fragment(R.layout.fragment_list) {
    lateinit var mainActivity:MainActivity
    lateinit var binding: FragmentListBinding

    override fun onCreateView( inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?
    ): View? {
        binding = FragmentListBinding.inflate(inflater,container,false)
        binding.btnNext.setOnClickListener { mainActivity?.goDetail()}
        return binding.root
    }
    override fun onAttach(context: Context) {
        super.onAttach(context)
        if(context is MainActivity) mainActivity = context
    }
}

[DetailFragment.kt]

class DetailFragment : Fragment() {
    lateinit var mainActivity:MainActivity
    lateinit var binding: FragmentDetailBinding

    override fun onCreateView( inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?
    ): View? {
        binding = FragmentDetailBinding.inflate(inflater,container,false)
        binding.btnback.setOnClickListener { mainActivity?.goBack()}
        return binding.root
    }
    override fun onAttach(context: Context) {
        super.onAttach(context)
        if(context is MainActivity) mainActivity = context
    }
}

[activity_main.xml]

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:visibility="visible"
    tools:context=".MainActivity">

    <TextView
        android:id="@+id/textView2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="16dp"
        android:text="Activity"
        android:visibility="visible"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <androidx.fragment.app.FragmentContainerView
        android:id="@+id/frameLayout"
        android:name="com.example.myapplication.ListFragment"
        android:layout_width="0dp"
        android:layout_height="0dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/textView2"
        tools:layout="@layout/fragment_list" />

</androidx.constraintlayout.widget.ConstraintLayout>

[fragment_detail.xml]

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#FFFFFF"
    android:clickable="true"
    tools:context=".DetailFragment"> 
    <TextView
        android:id="@+id/textView3"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="24dp"
        android:text="Detail"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.464"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" /> 
    <Button
        android:id="@+id/btnback"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="24dp"
        android:text="BACK"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.458"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/textView3" /> 
</androidx.constraintlayout.widget.ConstraintLayout>

[fragment_list.xml]

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".ListFragment"> 
    <TextView
        android:id="@+id/textView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/title_list"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" /> 
    <Button
        android:id="@+id/btnNext"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="24dp"
        android:text="NEXT"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.498"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/textView" /> 
</androidx.constraintlayout.widget.ConstraintLayout>

5) Passing values to Fragment
[MainActivity.kt]

class MainActivity : AppCompatActivity() {
    val binding by lazy { ActivityMainBinding.inflate(layoutInflater) }
    val listFragment by lazy { ListFragment() }
    val detailFragment by lazy { DetailFragment() }

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(binding.root)

        setFragment()
    }
    fun setFragment() {
        // pass value
        val bundle = Bundle()
        bundle.putString("key1", "List Fragment");
        bundle.putInt("key2", 20220226);
        listFragment.arguments = bundle
        //
        val transaction = supportFragmentManager.beginTransaction()
        transaction.add(R.id.frameLayout, listFragment)
        transaction.commit()
    }

    fun goDetail() {
        val transaction = supportFragmentManager.beginTransaction()
        transaction.add(R.id.frameLayout, detailFragment)
        transaction.addToBackStack("detail")
        transaction.commit()
    }
    fun goBack() {
        onBackPressed()
    }
}

[ListFragment.kt]

class ListFragment : Fragment(R.layout.fragment_list) {
    lateinit var binding: FragmentListBinding
    lateinit var mainActivity:MainActivity

    override fun onAttach(context: Context) {
        super.onAttach(context)
        if(context is MainActivity) mainActivity = context
    }
    override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?
    ): View? {
        binding = FragmentListBinding.inflate(inflater,container,false)
        with(binding) {
            arguments?.apply {
                textTitle.text = getString("key1")
                textValue.text = "${getInt("key2") }"
            }
            btnNext.setOnClickListener { mainActivity?.goDetail()}
        }
        return binding.root
    }
}

[fragment_list.xml]

<androidx.constraintlayout.widget.ConstraintLayout
 <TextView android:id="@+id/textView"
<Button android:id="@+id/btnNext"
 <TextView android:id="@+id/textTitle"
</androidx.constraintlayout.widget.ConstraintLayout

6) Create and deliver the value to Fragment displayed on the screen.
[MainActivity.kt]

class MainActivity : AppCompatActivity() {
    val binding by lazy { ActivityMainBinding.inflate(layoutInflater) }
    val listFragment by lazy { ListFragment() }
    val detailFragment by lazy { DetailFragment() }

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(binding.root)

        setFragment()
        binding.btnSend.setOnClickListener{
            listFragment.setValue("Pass Data")
        }

    }
    fun setFragment() {
        // pass value
        val bundle = Bundle()
        bundle.putString("key1", "List Fragment");
        bundle.putInt("key2", 20220226);
        listFragment.arguments = bundle
        //
        val transaction = supportFragmentManager.beginTransaction()
        transaction.add(R.id.frameLayout, listFragment)
        transaction.replace(R.id.frameLayout, listFragment)
        transaction.commit()
    }

    fun goDetail() {
        val transaction = supportFragmentManager.beginTransaction()
        transaction.add(R.id.frameLayout, detailFragment)
        transaction.addToBackStack("detail")
        transaction.commit()
    }
    fun goBack() {
        onBackPressed()
    }
}

[ListFragment.kt]

class ListFragment : Fragment(R.layout.fragment_list) {
    lateinit var mainActivity:MainActivity
    lateinit var binding: FragmentListBinding
    override fun onAttach(context: Context) {
        super.onAttach(context)
        if(context is MainActivity) mainActivity = context
    }
    override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?
    ): View? {
        binding = FragmentListBinding.inflate(inflater,container,false)
        with(binding) {
            arguments?.apply {
                textTitle.text = getString("key1")
                textValue.text = "${getInt("key2")}"
            }
            btnNext.setOnClickListener { mainActivity?.goDetail()}
        }
        return binding.root
    }
    fun setValue(value:String) {
        binding.textFromActivity.text = value
    }
}

[activity_main.xml]

<androidx.constraintlayout.widget.ConstraintLayout
<TextView android:id="@+id/textView2"
<androidx.fragment.app.FragmentContainerView android:id="@+id/frameLayout"
<Button android:id="@+id/btnSend"
</androidx.constraintlayout.widget.ConstraintLayout>

[fragment_list.xml]

<androidx.constraintlayout.widget.ConstraintLayout
<TextView android:id="@+id/textView"
<Button android:id="@+id/btnNext"
<TextView android:id="@+id/textTitle"
<TextView android:id="@+id/textValue"
<TextView android:id="@+id/textFromActivity"

6) Transferring the value from fragment to fragment

[build.gradle]

dependencies { 
    // fragment
    implementation "androidx.fragment:fragment-ktx:1.4.1"
}

[MainActivity.kt]

class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
    }
}

[SenderFragment.kt]

class SenderFragment : Fragment() {
    lateinit var binding:FragmentSenderBinding
    override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        binding = FragmentSenderBinding.inflate(inflater, container, false)
        with(binding) {
            btnYes.setOnClickListener{
                val bundle = bundleOf("senderKey" to "Yes")
                setFragmentResult("request", bundle)
            }
            btnNo.setOnClickListener{
                val bundle = bundleOf("senderKey" to "No")
                setFragmentResult("request", bundle)
            }
        }
        return binding.root
    }
}

[ReceiverFragment.kt]

class ReceiverFragment : Fragment() {
    lateinit var binding:FragmentReceiverBinding
    override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        binding = FragmentReceiverBinding.inflate(inflater, container, false)
        setFragmentResultListener("request") { key, bundle ->
            bundle.getString("senderKey")?.let { value ->
                binding.textView.text = value
            }
        }
        return binding.root
    } 
}

[activity_main.xml]

<androidx.constraintlayout.widget.ConstraintLayout
<androidx.fragment.app.FragmentContainerView
<androidx.fragment.app.FragmentContainerView
</androidx.constraintlayout.widget.ConstraintLayout

[fragment_receiver.xml]

<androidx.constraintlayout.widget.ConstraintLayout
<TextView android:id="@+id/textView"
<androidx.constraintlayout.widget.ConstraintLayout

[fragment_sender.xml]

<androidx.constraintlayout.widget.ConstraintLayout
<Button android:id="@+id/btnYes"
<Button android:id="@+id/btnNo"
</androidx.constraintlayout.widget.ConstraintLayout

[Android Studio|Kotlin] Activity

kaggle_study — Tue, 22 Feb 2022 07:16:01 +0000

1) Running sub activity from main activity
MainActivity(Button android:id="@+id/btnStart), SubActivity

[MainActivity.kt]

class MainActivity : AppCompatActivity() {

    val binding by lazy { ActivityMainBinding.inflate(layoutInflater) }

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(binding.root)

        binding.btnStart.setOnClickListener{
            val intent = Intent(this, SubActivity::class.java)
            startActivity(intent)
        }
    }
}

2) Sending and receiving activity values
2-1) Pass values from main to sub.

[MainActivity.kt]

class MainActivity : AppCompatActivity() {

    val binding by lazy { ActivityMainBinding.inflate(layoutInflater) }

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(binding.root)

        binding.btnStart.setOnClickListener{
            val intent = Intent(this, SubActivity::class.java)
            intent.putExtra("from1", "hello Bundle")
            intent.putExtra("from2", 2020)
            startActivity(intent)
        }
    }
}

[activity_sub.xml ]

TextView android:id="@+id/to1"
TextView android:id="@+id/to2"

[SubActivity.kt]

class SubActivity : AppCompatActivity() {
    val binding by lazy { ActivitySubBinding.inflate(layoutInflater) }
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(binding.root)

        with(binding) {
            to1.text = intent.getStringExtra("from1")
            to2.text = "${intent.getIntExtra("from2", 0) }"
        }
    }
}

2-2) Return the value to MainActivity.kt while exiting SubActivity.kt
https://developer.android.com/training/basics/intents/result
registerForActivityResult() * startActivityForResult is deprecated

[MainActivity.kt]

class MainActivity : AppCompatActivity() {

    val binding by lazy { ActivityMainBinding.inflate(layoutInflater) }

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(binding.root)

        val startForResult = registerForActivityResult(ActivityResultContracts.StartActivityForResult()) { result: ActivityResult ->
            if (result.resultCode == Activity.RESULT_OK) {
                val intent = result.data
                intent?.getStringExtra("returnValue")?.let { message ->
                    Toast.makeText(this, message, Toast.LENGTH_LONG).show()
                }
            }
        }
        binding.btnStart.setOnClickListener{
            val intent = Intent(this, SubActivity::class.java)
            intent.putExtra("from1", "hello Bundle")
            intent.putExtra("from2", 2020)
            startForResult.launch(intent) 
        }
    }
}

[activity_main.xml]

<androidx.constraintlayout.widget.ConstraintLayout
TextView android:id="@+id/textView2"
Button android:id="@+id/btnStart"
<androidx.constraintlayout.widget.ConstraintLayout

[SubActivity.kt]

class SubActivity : AppCompatActivity() {
    val binding by lazy { ActivitySubBinding.inflate(layoutInflater) }
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(binding.root)

        with(binding) {
            to1.text = intent.getStringExtra("from1")
            to2.text = "${intent.getIntExtra("from2", 0) }"
            btnClose.setOnClickListener{
                val returnIntent = Intent()
                returnIntent.putExtra("returnValue", editMessage.text.toString())
                setResult(Activity.RESULT_OK, returnIntent)
                finish()
            }
        }
    }
}

[activity_sub.xml]

<androidx.constraintlayout.widget.ConstraintLayout
TextView android:id="@+id/textView"
TextView android:id="@+id/to1"
TextView android:id="@+id/to2"
EditText android:id="@+id/editMessage"
Button android:id="@+id/btnClose"
<androidx.constraintlayout.widget.ConstraintLayout

[Android Studio] Basic Resource Layout

kaggle_study — Mon, 21 Feb 2022 06:37:03 +0000

OverView

ConstraintLayout (Constraint(제약조건) 설정만으로 화면 구성)
LinearLayout
FrameLayout

Bias 위치 조절 버튼
Aspect Ratio 가로세로비

ConstraintLayout

① View Options : 제약조건을 화면에 표시하거나 숨길 수 있다.
② Auto Connect : 오토 커넥트가 켜진 상태에서 위젯을 컨스트레인트 레이아웃에 가져다 놓으면 기본 컨스트레인트를 연결해준다.
③ Default Margin : 컨스트레인트 연결 시 설정한 만큼 기본 마진값을 적용한다.
④ Clear Constraints : 화면상의 모든 컨스트레인트를 제거한다. 개별로 제거할 때는 위젯에 마우스 포인터를 올리면 나타나는 동일한 모양의 아이콘을 클릭한다.
⑤ Infer Constraints : 오토 커넥트를 끄고 작업할 때 사용한다. 가까운 위젯이나 레이아웃에 2개 이상의 컨스트레인트를 연결한다.
⑥ Pack : 여러 개의 위젯을 동시에 선택한 상태에서 크기를 조절할 때 사용한다. 선택된 위젯들의 상태에 따라서 크기가 조절될 때도 있고, 위치가 조절될 때도 있다.
⑦ Align : 선택된 위젯들을 정렬해준다.
⑧ GuideLine : layout 안의 모든 위젯에 대해 공통의 여백을 지정할 때 사용한다. 가로 또는 세로 가이드라인을 삽입하면 위젯들은 가이드라인에 컨스트레인트를 연결할 수 있다.

GuideLine
ConstraintLayout에만 사용할 수 있는 보조 도구다.
GuideLine을 Drag해서 화면 임의의 위치에 가져다 놓으면 layout 안에 배치되는 위젯에 가상의 Anchor Point를 제공한다.

LinearLayout
위젯을 가로 또는 세로로 한 줄로 배치하기 위한 layout.

orientation 속성
하위 버전의 android studio에서는 필수 속성이었지만, 3.1부터는 입력하지 않으면 horizontal가 적용돼 가로로 배치된다. (horizontal, vertical만 변경해주면 기존에 배치되어 있던 위젯들도 방향을 바꿀 수 있다.)

layout_weight 속성
레이아웃 안에 배치되는 위젯의 크기를 비율로 나타낼 수 있는 옵션. LinearLayout에 배치되는 위젯의 layout_weight 속성은 기본 설정값이 1이다.

gravity 속성

layout_gravity 속성
속해있는 layout(부모 layout)을 기준으로 나의 위치를 설정할 때 사용. 주로 LinearLayout과 FrameLayout 에서 사용된다.

LinearLayout을 사용하기 위해 ConstraintLayout 안에 LinearLayout을 추가할 수도 있지만 Layout이 중첩되면 그만큼 그래픽 처리 속도가 느려지기 때문에 기본 Layout인 ConstraintLayout을 LinearLayout으로 바꾼 후에 작업을 한다.

주의사항
LinearLayout과 같은 일반 layout들은 화면 크기(높이, 넓이)를 넘어가는 위젯이 삽입돼도 Scroll이 되지 않는다.
이럴 때는 최상위 layout을 Scroll 할 수 있는 요소로 감싸야 한다. Scroll View를 사용하려면 ① 기존 layout(ConstraintLayout)을 Scroll View로 변경해서 사용하거나, ② 기본 layout 안에 Scroll View를 추가해야 한다.

example)

1) Change [android.constraintlayout.widget.ConstraintLayout] -> [ScrollView]
2) LinearLayout을 Drag하여 ScrollView 안에 놓는다.
3) 그 다음 LinearLayout 안에 Button을 20개 정도 삽입한 다음 emulator를 실행해보면 scroll 되는 것을 확인할 수 있다.

*FrameLayout *

[Android Studio|Kotlin] Binding

kaggle_study — Sun, 20 Feb 2022 20:39:16 +0000

viewBinding

    buildFeatures {
        viewBinding = true
    }

Example 1 ) setOnClickListener

[MainActivity.kt]

class MainActivity : AppCompatActivity() {

    val binding by lazy { ActivityMainBinding.inflate(layoutInflater) }

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(binding.root)

        binding.btnSay.setOnClickListener {
            binding.textSay.text = "Hello Kotlin"
        }

    }
}

[activity_main.xml]

    <TextView
        android:id="@+id/textSay"
        android:layout_width="77dp"
        android:layout_height="19dp"
        android:text="Hello World!"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <Button
        android:id="@+id/btnSay"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="31dp"
        android:text="Button"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/textSay" />

Example 2-1 ) addTextChangedListener
[activity_main.xml]

    <TextView
        android:id="@+id/textView"   />

    <EditText
        android:id="@+id/editText" />

class MainActivity : AppCompatActivity() {

    val binding by lazy { ActivityMainBinding.inflate(layoutInflater) }

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(binding.root)

        with(binding) {
            editText.addTextChangedListener{
                Log.d("EditText012345", "Current Value=${it.toString()}")
            }
        }
    }
}

Example 2-2 ) addTextChangedListener
[MainActivity.kt]

class MainActivity : AppCompatActivity() {

    val binding by lazy { ActivityMainBinding.inflate(layoutInflater) }

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(binding.root)

        with(binding) {
            editText.addTextChangedListener{ editable ->
                Log.d("EditText012345", "Current Value=${editable.toString()}")
            }
        }
    }
}

Example 2-3 ) addTextChangedListener
Depending on the version of Android Studio used, the parameters of the automatically generated function may be different.
like .. [s: Editable?], [s: CharSequence?], [p0: Editable?], [edit: Editable?]

[MainActivity.kt]

class MainActivity : AppCompatActivity() {

    val binding by lazy { ActivityMainBinding.inflate(layoutInflater) }

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(binding.root)

        binding.editText.addTextChangedListener(object : TextWatcher{
            override fun beforeTextChanged(p0: CharSequence?, p1: Int, p2: Int, p3: Int) {
            }
            override fun onTextChanged(p0: CharSequence?, p1: Int, p2: Int, p3: Int) {
            }
            override fun afterTextChanged(p0: Editable?) {
                Log.d("EditText012345", "Current Value=${p0.toString()}")
                binding.textView.text = p0.toString()
            }
        })
    }
}

Example 3-1 ) Check if the entered characters are 8 or more characters like when checking ID when logging in
[MainActivity.kt]


class MainActivity : AppCompatActivity() {

    val binding by lazy { ActivityMainBinding.inflate(layoutInflater) }

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(binding.root)

        with(binding) {
            editText.addTextChangedListener{
                if (it.toString().length >= 8) {
                    Log.d("EditText012345", "over 8=${it.toString()}")
                }
            }
        }
    }
}

Example 3-2 ) Check if the entered characters are 8 or more characters like when checking ID when logging in
[MainActivity.kt]

class MainActivity : AppCompatActivity() {

    val binding by lazy { ActivityMainBinding.inflate(layoutInflater) }

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(binding.root)

        binding.editText.addTextChangedListener(object : TextWatcher{
            override fun beforeTextChanged(p0: CharSequence?, p1: Int, p2: Int, p3: Int) {
            }
            override fun onTextChanged(p0: CharSequence?, p1: Int, p2: Int, p3: Int) {
            }
            override fun afterTextChanged(p0: Editable?) {
                if (p0.toString().length >= 8 ) {
                    Log.d("EditText012345", "over 8=${p0.toString()}")
                }
            }
        })
    }
}

Example 4-1 ) CHECKBOX
{ compoundButton, b -> }
{ compoundButton, i -> }
{ buttonView, isChecked -> }

[MainActivity.kt]

class MainActivity : AppCompatActivity() {

    val binding by lazy { ActivityMainBinding.inflate(layoutInflater) }

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(binding.root)

        with(binding) {
            checkApple.setOnCheckedChangeListener (listener)
            checkBanana.setOnCheckedChangeListener (listener)
            checkOrange.setOnCheckedChangeListener (listener)
        }
    }
    var listener = CompoundButton.OnCheckedChangeListener { buttonView, isChecked ->
        if (isChecked) {
            when (buttonView.id) {
                R.id.checkApple -> Log.d("CheckBox", "Apples have been selected.")
                R.id.checkBanana -> Log.d("CheckBox", "Banana have been selected.")
                R.id.checkOrange -> Log.d("CheckBox", "Orange have been selected.")
            }
        } else {
            when (buttonView.id) {
                R.id.checkApple -> Log.d("CheckBox", "Apple are deselected.")
                R.id.checkBanana -> Log.d("CheckBox", "Banana are deselected.")
                R.id.checkOrange -> Log.d("CheckBox", "Orange are deselected.")
            }
        }
    }
}

Example 4-2 ) CHECKBOX
{ compoundButton, b -> }
{ buttonView, isChecked -> }
[MainActivity.kt]

class MainActivity : AppCompatActivity() {

    val binding by lazy { ActivityMainBinding.inflate(layoutInflater) }

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(binding.root)

        with(binding) {
            var listener = CompoundButton.OnCheckedChangeListener { compoundButton, b -> 
                if (b) {
                    when (compoundButton.id) {
                        R.id.checkApple -> Log.d("CheckBox", "Apples have been selected.")
                        R.id.checkBanana -> Log.d("CheckBox", "Banana have been selected.")
                        R.id.checkOrange -> Log.d("CheckBox", "Orange have been selected.")
                    }
                } else {
                    when (compoundButton.id) {
                        R.id.checkApple -> Log.d("CheckBox", "Apple are deselected.")
                        R.id.checkBanana -> Log.d("CheckBox", "Banana are deselected.")
                        R.id.checkOrange -> Log.d("CheckBox", "Orange are deselected.")
                    }
                }
            }
            checkApple.setOnCheckedChangeListener (listener)
            checkBanana.setOnCheckedChangeListener (listener)
            checkOrange.setOnCheckedChangeListener (listener)
        }

    }
}

Example 5 ) ToggleButton, Switch
[MainActivity.kt]

class MainActivity : AppCompatActivity() {

    val binding by lazy { ActivityMainBinding.inflate(layoutInflater) }

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(binding.root)

        with(binding) {
            toggleButton.setOnCheckedChangeListener { compoundButton, isChecked ->
                textToggle.text = if(isChecked) "On" else "Off"
            }
            switchButton.setOnCheckedChangeListener { compoundButton, isChecked ->
                textSwitch.text = if(isChecked) "On" else "Off"
            }
        }
    }
}

Example 6 ) ProgressBar
LinearLayout android:id="@+id/progressLayout"
[MainActivity.kt]

class MainActivity : AppCompatActivity() {

    val binding by lazy { ActivityMainBinding.inflate(layoutInflater) }

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(binding.root)

        with(binding) {
            // MAIN THREAD
            showProgress(true)
            thread(start=true) {
                Thread.sleep(3000)
                runOnUiThread {
                    showProgress(false)
                }
            } // SUB THREAD
        } // MAIN THREAD
    }

    fun showProgress(show: Boolean){
        binding.progressLayout.visibility = if(show) View.VISIBLE else View.GONE
    }
}

Example 7 ) SeekBar
SeekBar android:id="@+id/seekBar"
TextView android:id="@+id/textView"
(SeekBar: SeekBar?, progress: Int, fromUser: Boolean)
(p0: SeekBar?, p1: Int, p2: Boolean)
[MainActivity.kt]

class MainActivity : AppCompatActivity() {

    val binding by lazy { ActivityMainBinding.inflate(layoutInflater) }

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(binding.root)

        with(binding) {
            seekBar.setOnSeekBarChangeListener(object :SeekBar.OnSeekBarChangeListener {
                override fun onProgressChanged(p0: SeekBar?, p1: Int, p2: Boolean) {
                    textView.text = "$p1"
                }
                override fun onStartTrackingTouch(p0: SeekBar?) {}
                override fun onStopTrackingTouch(p0: SeekBar?) {}
            })
        }
    }
}

Example 8 ) Rating Bar
RatingBar android:id="@+id/ratingBar"
TextView android:id="@+id/textView"
{ ratingBar, fl, b -> }
{ ratingBar, rating, fromUser -> }
[MainActivity.kt]


class MainActivity : AppCompatActivity() {

    val binding by lazy { ActivityMainBinding.inflate(layoutInflater) }

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(binding.root)

        with(binding) {
            ratingBar.setOnRatingBarChangeListener { ratingBar, fl, b ->
                textView.text = "$fl"
            }
        }
    }
}

Android Studio basic settings

kaggle_study — Sun, 20 Feb 2022 04:13:55 +0000

Android SDK basic settings
[File > Settings > Appearance & Behavior > System Settings > Android SDK > SDK Tools]

Android SDK Build-Tools ::리소스 아이디를 가지고 있는 R파일을 생성하고 설치 파일인 APK 파일을 최적화하는 도구. include tool that convert Java Bytecode to Dalvik Bytecode.
(Android Emulator)
( Android SDK Platform-Tools)
Android SDK Tools
Intel x86 Emulator Accelerator (HAXM Installer) :: 에뮬레이터의 처리 속도를 빠르게 해주는 하드웨어 가속기

When developing multiple projects at the same time.
[File > Settings > Appearance & Behavior > System Settings]

Uncheck [Reopen projects on startup]

viewBinding

    buildFeatures {
        viewBinding = true
    }

[values>themes>themes.xml]

<item name="windowActionBar">false</item>
<item name="windowNoTitle">true</item>

color / #FFC107

notepad (Google Play Store)

kaggle_study — Sun, 20 Feb 2022 02:11:30 +0000

AAB 파일로 빌드된 파일을 앱스토어에 등록한다.

Different Java Kotlin in Android Studio

kaggle_study — Sun, 20 Feb 2022 01:45:16 +0000

onClickListener

Java

class ButtonActivity extends Activity {
      protected void onCreate(Bundle saveInstance) {
            Button button = findViewById(R.id.button);
            button.setOnClickListener(new View.OnClickListener() {
                  public void onClick(View view) {
                        System.out.print("Hello World");
                  }
            }
      }
}

Kotlin

class ButtonActivity : Activity() {
      override fun onCreate(saveInstance: Bundle?) {
            button.setOnClicklistener {
                  print("Hello World")
            }
      }
}

[Android Studio|Kotlin] RecyclerView, setOnClickListener

kaggle_study — Fri, 18 Feb 2022 18:57:34 +0000

Youtube:

[app>values>themes>themes.xml]

        <!-- Customize your theme here. -->
        <item name="windowActionBar">false</item>
        <item name="windowNoTitle">true</item>

[Gradle Scripts>build.gradle(Module:recyclerview.app)]

    // retrofit
    implementation 'com.squareup.retrofit2:retrofit:2.9.0'
    implementation 'com.squareup.retrofit2:converter-gson:2.9.0'

[app>manifests>AndroidManifest.xml]

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.recyclerview">

    <uses-permission android:name="android.permission.INTERNET"/>

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/Theme.Recyclerview">
        <activity
            android:name=".MainActivity"
            android:exported="true">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application> 
</manifest>

[app>java>com.example...>ApiService]

package com.example.recyclerview

import retrofit2.Call
import retrofit2.http.GET

interface ApiService {
    @GET("/apptech")
    fun getPosts(): Call<MutableList<PostModel>>
}

[app>java>com.example...>MainActivity]

package com.example.recyclerview

import android.content.Intent
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.util.Log
import android.view.View
import android.widget.Button
import android.widget.Toast
import androidx.recyclerview.widget.LinearLayoutManager
import androidx.recyclerview.widget.RecyclerView
import com.example.recyclerview.*
import retrofit2.Call
import retrofit2.Callback
import retrofit2.Response

class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        val recyclerView = findViewById<RecyclerView>(R.id.myRecyclerView)
        val serviceGenerator = ServiceGenerator.buildService(ApiService::class.java)
        val call = serviceGenerator.getPosts()
        call.enqueue(object : Callback<MutableList<PostModel>>{
                override fun onResponse(call: Call<MutableList<PostModel>>, response: Response<MutableList<PostModel>>) {
                    if (response.isSuccessful) {
                        recyclerView.apply {
                            layoutManager = LinearLayoutManager(this@MainActivity)
                            adapter = PostAdapter(response.body()!!)
                        }
                    }
                }

                override fun onFailure(call: Call<MutableList<PostModel>>, t: Throwable) {
                    t.printStackTrace()
                    Log.e("error", t.message.toString())
                }
            })
    }
}

[app>java>com.example...>PostAdapter]

package com.example.recyclerview

import android.content.Intent
import android.net.Uri
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.TextView 
import androidx.core.content.ContextCompat
import androidx.recyclerview.widget.RecyclerView

class PostAdapter(val postModel: MutableList<PostModel>):RecyclerView.Adapter<PostAdapter.PostViewHolder>() {
    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): PostViewHolder {
        val view = LayoutInflater.from(parent.context).inflate(R.layout.card_post,parent,false)
        return PostViewHolder(view )
    }

    override fun getItemCount(): Int {
        return postModel.size
    }



    override fun onBindViewHolder(holder: PostViewHolder, position: Int) {
        return holder.bindView(postModel[position])
    }

    inner class PostViewHolder(itemView: View ) : RecyclerView.ViewHolder(itemView) {
        private val tvTitle: TextView = itemView.findViewById(R.id.tvTitle)
        private val tvBody: TextView = itemView.findViewById(R.id.tvBody)
        private val tvTime: TextView = itemView.findViewById(R.id.tvTime)

        fun bindView(postModel: PostModel){
            tvTitle.text = postModel.apptech_brand
            tvBody.text = postModel.apptech_title
            tvTime.text = postModel.apptech_time
            // for setOnClickListener
            itemView.setOnClickListener {
                var url = "${postModel.apptech_url}"
                val intent = Intent(Intent.ACTION_VIEW, Uri.parse(url))
                ContextCompat.startActivity(itemView.context, intent, null)
            }
        }

    } 
}

[app>java>com.example...>PostModel]

package com.example.recyclerview

data class PostModel(
    val apptech_brand: String? = null,
    val apptech_title: String? = null,
    val apptech_period: String? = null,
    val apptech_point: Int? = null,
    val apptech_time: String? = null,
    val apptech_url: String? = null
)

[app>java>com.example...>ServiceGenerator]

package com.example.recyclerview

import okhttp3.OkHttpClient
import retrofit2.Retrofit
import retrofit2.converter.gson.GsonConverterFactory

object ServiceGenerator {
    private val client = OkHttpClient.Builder().build()
    private val retrofit = Retrofit.Builder()
        .baseUrl("https://********.herokuapp.com")
        .addConverterFactory(GsonConverterFactory.create())
        .client(client)
        .build()

    fun <T> buildService(service: Class<T>): T {
        return retrofit.create(service)
    }
}

[app>res>drawable>border_a.xml]

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android">
    <solid android:color="#FFD0D0"></solid>
    <stroke android:width="3dp" android:color="#FF8484"/>
    <corners android:radius="15dp"/>
</shape>

[app>res>layout>activity_main.xml]

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<androidx.recyclerview.widget.RecyclerView
    android:id="@+id/myRecyclerView"
    android:layout_width="match_parent"
    android:layout_height="match_parent" />
</FrameLayout>

[app>res>layout>card_post.xml]

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    xmlns:tools="http://schemas.android.com/tools"
    android:paddingTop="8dp"
    android:paddingBottom="8dp"
    android:paddingLeft="15dp"
    android:layout_marginTop="4dp"
    android:layout_marginBottom="4dp"
    android:layout_marginLeft="8dp"
    android:layout_marginRight="8dp"
    android:orientation="horizontal"
    android:background="@drawable/border_a">

    <TextView
        android:id="@+id/tvTitle"
        tools:text="Hello Title"
        android:layout_width="80dp"
        android:layout_height="match_parent"
        android:textColor="@color/black"
        android:textSize="20sp" />

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="vertical"
        android:paddingLeft="15dp"
        android:paddingRight="15dp" >

        <TextView
            android:id="@+id/tvBody"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:textSize="14sp"
            tools:text="Hello Body"
            android:textAlignment="center"/>

        <TextView
            android:id="@+id/tvTime"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:textSize="14sp"
            tools:text="Hello Time"
            android:textAlignment="center"/> 
    </LinearLayout> 
</LinearLayout>

Heroku Deploy

kaggle_study — Mon, 14 Feb 2022 16:38:46 +0000

heroku login
git init
heroku git:remote -a appname
git add .
git commit -am "make it better"
git push heroku master

rm -rf .git

! [rejected] master -> master (non-fast-forward)
error: failed to push some refs to 'https://git.heroku.com/appname.git'
hint: Updates were rejected because the tip of your current branch is behind
hint: its remote counterpart. Integrate the remote changes (e.g.
hint: 'git pull ...') before pushing again.
hint: See the 'Note about fast-forwards' in 'git push --help' for details.

git push heroku HEAD:master --force

Precautions
https://velog.io/@han0707/django-heroku-error

memo, Window10 with Ubuntu

kaggle_study — Fri, 11 Feb 2022 15:58:02 +0000

source activate virtual name

https://stackoverflow.com/questions/39281594/error-1698-28000-access-denied-for-user-rootlocalhost

https://stackoverflow.com/questions/62987154/mysql-wont-start-error-su-warning-cannot-change-directory-to-nonexistent