DEV Community: Kuan Peng

Learnings From Building A Weather App

Kuan Peng — Fri, 03 Jul 2020 22:31:46 +0000

Summary

This post is about learnings from my experience building apps while following this Udemy Course.
I ended up adding quite a bit to the base app, and I'm glad I did - it was really good learning to experiment with different frameworks and such. It took some time - about 6 hours or so...

Class Goal

Building a weather app, that fetches and displays information from an existing public API.

Class Learning Goal:

Learn how to talk to public APIs and parse JSON from responses.

My personal Goals

As part of trying to build this app, I wanted to learn more about:

Dependency Injection
JSON parsing frameworks

Most importantly I wanted to build a beautiful app similar to the Yahoo Weather app, which changed its background based on current location.

Result

github

kuanp / DaWeatherApp

DaWeatherApp

See https://dev.to/kuanp/learnings-from-building-a-weather-app-3l88

View on GitHub

Screenshot / Demo

UX improvements to the base app

Beautiful backgrounds appropriate to the City and the current weather in the city.
Auto completion suggestions for city names; case insensitive search
Toast messages for incorrect spelling
Visible Search / Weather panels that doesn't obstruct view of the photos

Learnings

APIs

Leverage Unsplash for great images. Unsplash APIs are quite easy and useful; used the "portrait" mode to search for photos that doesn't require resizing as much
API tokens can be stored locally via BuildConfigs and git-ignored so they don't appear on the searchable web. See this guide. Not the most secure for production, but good enough for learning projects.
Retrofit is such a nice library to use when the API use cases are super simple. It's ability to quickly generated a usable client with auto-json parsing abilities is great (make sure to use the converters like GsonConverter).
Gson is a lot easier to use than I expected. Good synergy w/ Lombok.
OkHttpInterceptors are good but a little bit of a pain. I read that OkHttpClients should be shared generally, but when they need to interface w/ separate services, I think we need to create a client for each service.

Architecture learnings

Dagger takes a little setting up to get going (you have to create an Application Class in addition to the basic activities, and the entry point is for some reason in the activity oncreate). But once it's set up, it's a great framework that makes dependencies super easy to manage. I'll try Hilt next.
How to organize package structure for D.I. is still a mystery to me.
Always use Java8. Streams are just too powerful to not use.

Android Learnings

AsyncTask isn't that bad on the surface... I probably should explore alternatives given it's deprecated.
ArrayAdaptors are a lot more finicky that I had expected. They require a layout (either my own or from android) to know how render a TextView. I made the mistake of passing them the activity layout, not realizing that made the dropdown box render the whole activity and crash the app.
Animating background changes seems to be a pain. Didn't figure out how to do this. Good next actions.
Toast can have gravity and appear in customized locations on the screen.
Hiding keyboard is hard, apparently. Also getting Enter key pressed to act like a submit button was interesting - use view.setOnKeyListener . * Careful when reading from file, because it could cost a lot of latency on startup. I honestly think I should've done it async... * Semi-Transparent layouts can help display the image underneath and at the same time help with making texts more legible.

Further Meaningful Augmentations

Add Animations/Transitions to photo changes, as I've mentioned
Add Temperature, humidity, etc
Save preferences
Make the TextLayouts that make things legible a color gradient rather than a single grey color. This could also blur the background as well..

That's all! Thanks for reading...

So You Think You Know Kpop (Android App)

Kuan Peng — Mon, 29 Jun 2020 05:20:37 +0000

Summary

Built a celebrity guessing app as part of clip #84 of The Complete Android 8.0 Oreo Developer Course by Rob Percival and Nick Walter.

The goal of this exercise was to practice downloading things from the internet using AyncTask (which is actually deprecated...).

Deviated somewhat from the task at hand as the website used in the course is no longer available. So I drew inspiration from Kpop.

Code

kuanp / SoYouThinkYouKnowKpop

Modified version of Guess The Celebrity

Screenshot

Main Challenge

The biggest challenge for this assignment is finding a website that has nice looking HTML to parse. I sourced content from https://kingchoice.me; this website contains a lot of "celebrity lists" with nice HTML.

For example: https://kingchoice.me/topic-hot-100-kpop-idols-rankings-2019-close-dec-31-1225.html

I also found it to be overly tedious to try to create a regex to search through HTML. After all, it's semi-structured information, so instead I used Jsoup to parse the HTML and get the elements I needed. Others may want to do the same. Tutorials: link

Additional interesting things of note

Used Java8; the stream / lambda paradigm is very powerful
Used Lombok; its EqualsAndHashCode capability is great for deduping objects.
Always fun to try to break the logic into many classes
Was too lazy to properly handle exceptions. Oh well...
Wonder how to use Futures or other concurrency features; pretty sure I locked UI thread while loading stuff for this one.

Just built a brain trainer app

Kuan Peng — Mon, 15 Jun 2020 02:48:04 +0000

Mostly a recording for my own use while I take on https://www.udemy.com/course/the-complete-android-oreo-developer-course/learn/lecture/8339458#content

Summary of learnings:

lombok is useful, easy to use for android
adding dependencies to projects is done via build.gradle
Having a different activity allow users to use the "back" button as part of interactions.
may start learning how to unit tests some of these things, getting a bit complex and need to catch bugs.

Some notes:

Might be a good idea to get a google play account so I can send the app to other people to sue
Could implement difficulty level + highest score

Time taken:

About 3 hours
Trying to build a grid using Relative Layouts is a bit of a pain
- Might want to use fragments or some other programmatic way to do this. Might just use GridView since it's convenient.