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Vivian
Vivian

Posted on

OSD600 - My Fourth Hacktoberfest Contribution

1. Introduction

This semester, I also attend to the Mobile App Development - Android (MAP524) which is about developing mobile applications for the Android platform. I feel quite interested in designing a mobile app so I searched for all android projects with Hacktoberfest label in Git Hub. Luckily, I found one named Androapps, this project contains a lot of Android applications which were contributed by many developers. And I decided to engage in.

2. The issue

The issue I was assigned is to create a Weather forecast application. The maintainer is quite easy-going, he was not be strict about how the app should look like but gave me the freedom to be creative.

3. The solution

Here are steps I did to create my application:

  • Find a weather API
    • After a quick research, I decided to use Open Weather Map which returns JSON objects. For more information about how to use this, please read the guide.
  • Design the UI

    • Since I just learned about some layouts and basic views in MAP524 so I am going to design a simple UI with an EditText to get user input, a Button to submit the input, some TextView to display information and a ImageView for app background.
    • The UI design: Image description
  • Implement Java code

    1) Using Volley library to request data from the API.

    2) Get JSON objects/data from response:

 // gets JSON objects
JSONObject mainWeather = response.getJSONObject("main");
JSONObject weather = response.getJSONArray("weather").getJSONObject(0);
JSONObject windInfo = response.getJSONObject("wind");
JSONObject sunInfo = response.getJSONObject("sys");
int humidity = mainWeather.getInt("humidity");
double windSpeed = windInfo.getDouble("speed");
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3) Calculate data:

// converts unix time stamp to date
Date dateInfo = new Date(response.getLong("dt")*1000);
Date sunRiseD = new Date(sunInfo.getLong("sunrise") * 1000);
Date sunSetD = new Date(sunInfo.getLong("sunset") * 1000);
int timezone = response.getInt("timezone");

 // formats output and changes timezone
@SuppressLint("SimpleDateFormat") SimpleDateFormat dateFormat = new SimpleDateFormat("EEEE, dd MMM yyyy");         
dateFormat.setTimeZone(TimeZone.getTimeZone(ZoneOffset.ofTotalSeconds(timezone)));

@SuppressLint("SimpleDateFormat") SimpleDateFormat timeFormat = new SimpleDateFormat("HH:mm a");           
timeFormat.setTimeZone(TimeZone.getTimeZone(ZoneOffset.ofTotalSeconds(timezone)));

 int tempC = (int) (Math.round(mainWeather.getDouble("temp") - 273.15));
 int feelTemp = (int)(Math.round(mainWeather.getDouble("feels_like") - 273.15));
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4) Display data appropriately to the UI:

currentDate.setText(dateStr);
currentTime.setText(timeStr);
temperature.setText(tempC + "°");
location.setText(city.toUpperCase());          
displayWeather.setText(weather.getString("main"));
feels.setText("Feels like: " + feelTemp + "°C");
humid.setText(humidity + "%");
wind.setText(windSpeed + "m/s");
sunRise.setText(sunRiseStr);
sunSet.setText(sunSetStr);
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5) Function to set ImageView and text color based on time

void setBackground(int hour, ImageView imgV){...}
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View the app

The maintainer reviewed the PR very quick, he merged my PR without any requirements.

If you want to get more information about the app, please take a look to this PR.

4. Overall

I gained a lot of new information after completing this issue. It was painful and enjoyable at the same time.
Thank you for reading the post.

Happy coding!

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