LetsLearnAndroid

Files and instructions for learning Android.

Lesson 1

Setup Guide

• Install Android Studio

  • Download Android Studio from
  • (Mac) http://developer.android.com/sdk/index.html
  • Open Android Studio
    • Import/Don’t settings from previous installation
    • Use default installation for setting up sdk: ~/Library/Android/sdk ####Project setup

• Open Android Studio

  • Start New Android Project
  • New Project
    • Application Name: MiiDroid
    • Company Domain: unique identifier
  • Target Android Device
    • 5.0
  • Add Target Activity
    • Empty activity
  • Customize:
    • MainActivity
  • Finish
  • Change the build tool version to 23.0.1

• Add version control

  • Click on vcs
  • Enable version control
  • Select Git
  • Add .idea to .gitignore
  • Add and Commit changes

• Github

  • Create a new github respository
  • Add remote
  • Push to Github

• CircleCI

  • Add Project
  • Link to GitHub
  • Build your project

• HockeyApp

  • http://hockeyapp.net/features/
  • Create free account
  • Check “I’m a developer”
  • Setting up devices
    • Guided
    • Navigate to URL
    • Install HockeyApp app
  • Create App
    • Android - alpha
  • Create scripts folder in project
    • Create deployHockeyApp.sh under scripts
  • Create circle.yml
    • For more information visit https://github.com/Originate/guide/blob/master/android/guide/Continuous%20Deployment.md
  • Commit the files, don't push!
  • On HockeyApp
    • Account settings > API Tokens > Create API Token
      • App : your app
      • Rights : Upload & Release
      • Name : CircleCI
  • On Circle CI
    • Go to project settings > Enviroment variables
      • HOCKEYAPP_APP_IDENTIFIER : copy from hockeyapp project
      • HOCKEYAPP_EXPORT_APK_PATH : app/build/outputs/apk/app-debug.apk
      • HOCKEYAPP_TOKEN : copy from hockyapp account settings
  • Push to github.

Lesson 2

First Activity

• Running The Application:

  • Open up Android Studio
  • Select MiiDroid
  • Setting up device
    • On the device: Settings -> developer options -> Enable USB Debugging
    • Plug device into the laptop
    • Click on the green play button and select the device from the list. The app should launch on the device
  • Setting up emulator
    • Launch the Android Virtual Device Manager
      • In Android Studio, select Tools > Android > AVD Manager, or click the AVD Manager icon in the toolbar.
      • Select the desired hardware, selection system version (5.0+ for our project)
      • Verify configurations and then click finish.
      • Click on green play button and select and select the emulator that you just created
      • The app should launch on the emulator
    • For more details please visit: http://developer.android.com/intl/es/training/basics/firstapp/running-app.html

• Building your first user interface

  • Open up your project in Android studio.
    • All your layout files are contained in res/layout folder
    • Open up activity_main.xml and examine the layout
    • Change the top level layout to LinearLayout with vertical orientation
    • Change TextView to EditText: id = @+id/et_username, text->height=wrap_content, width=match_parent, text=username`
    • Add another EditText with similar contraints and set text to password, id = @+id/et_password
    • Add a Button with text Login, id = @+id/btn_login
    • Open MainActivity from java/your.package.name/MainActivity
    • Set Listeners
      • Create instance variables for the Button and the two EditText
      • In the onCreate of your activity
      • Set click listener on the button
      • mBtnLogin.setOnClickListener(this);
      • Implement the click listener to print out user name and password on button click

Lesson 3

Intents

• Launch Android Studio and Open Up MiiDroid
• Create a new Activity called MenuActivity
• Open up MenuActivity and navigate to its layout file
• Add a scroll view as the root view
• Add a button called Send Implicit intent
• Implement functionality for sending a implicit ACTION_SEND intent with text Hello World

  // Create the text message with a string
  Intent sendIntent = new Intent();
  sendIntent.setAction(Intent.ACTION_SEND);
  sendIntent.putExtra(Intent.EXTRA_TEXT, textMessage);
  sendIntent.setType("text/plain");
  
  // Verify that the intent will resolve to an activity
  if (sendIntent.resolveActivity(getPackageManager()) != null) {
      startActivity(sendIntent);
  }

• Open up main activity and adjust the current layout to center on screen
• Add a new text view which will be used to display an error message
• Add a method called isValid(username, password) that returns a boolean
  • verify username and password against static data
• Create an Intent object to start MenuActivity and navigate the user to it on valid username/password
• Show error if username/password is incorrect.

Lesson 7

Service

• Create class MyIntentService extends IntentService

• Implement default constructor

  public MyIntent() {
    super("MyService");
  }

• Define TAG

  public static final String TAG = MyIntentService.class.getSimpleName();

• Override onHandleIntent(Intent intent)

  for (int i = 0; i < 5; i++) {
    try {
      Log.d(TAG, "Sleeping for 0.5 seconds " + i);
      Thread.sleep(500);
    } catch (InterruptedException e) {
      e.printStackTrace();
    }
  }

• Declare service in AndroidManifest.xml

  <service android:name=".service.MyIntentService" />

• Create new activity MyServiceActivity.java

• Add button btn_start_service in activity_my_service.xml

  <Button
    android:id="@+id/btn_start_service"
    android:text="@string/btn_start_service"
    android:layout_width="match_parent"
    android:layout_height="wrap_content" />

• onCreate

  findViewById(R.id.btn_start_service).setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View v) {
      Intent intent = new Intent(MyServiceActivity.this, MyIntentService.class);
      startService(intent);
    }	
  ;})

• Add new menu item in MenuActivity.java

  new MenuItem(MyServiceActivity.class, "Service Demo")

Lesson 8

MediaPlayer

• Update Gradle (2.14.1)
• Create package "media.player"
• New Empty Activity "MediaPlayerActivity"
• In MenuActivity, add New MenuItem "Media Player Demo"
• activity_media_player.xml
  • Change root to ScrollView with a LinearLayout
  • Add buttons
    • Play
    • Pause
    • Stop

<?xml version="1.0" encoding="utf-8"?>

<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
   xmlns:tools="http://schemas.android.com/tools"
   android:layout_width="match_parent"
   android:layout_height="wrap_content">

   <LinearLayout
       android:id="@+id/activity_media_player"
       android:layout_width="match_parent"
       android:layout_height="wrap_content"
       android:orientation="vertical"
       android:paddingBottom="@dimen/activity_vertical_margin"
       android:paddingLeft="@dimen/activity_horizontal_margin"
       android:paddingRight="@dimen/activity_horizontal_margin"
       android:paddingTop="@dimen/activity_vertical_margin"
       tools:context="meetup.droid.miidroid.media.player.MediaPlayerActivity">

       <Button
           android:id="@+id/btn_play"
           android:layout_width="match_parent"
           android:layout_height="wrap_content"
           android:text="@string/play_foreground" />

       <Button
           android:id="@+id/btn_pause"
           android:layout_width="match_parent"
           android:layout_height="wrap_content"
           android:text="@string/pause" />

       <Button
           android:id="@+id/btn_stop"
           android:layout_width="match_parent"
           android:layout_height="wrap_content"
           android:text="@string/stop" />

   </LinearLayout>
</ScrollView>

• Create "raw" folder under res
• Put music file into folder
• In MediaPlayerActivity
  • onClickListener
  • Implementing buttons

private MediaPlayer mMediaPlayer;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_media_player);

    findViewById(R.id.btn_play).setOnClickListener(this);
    findViewById(R.id.btn_stop).setOnClickListener(this);
    findViewById(R.id.btn_pause).setOnClickListener(this);

    mMediaPlayer = MediaPlayer.create(this, R.raw.viviq);
}

@Override
public void onClick(View v) {
    switch (v.getId()) {
        case R.id.btn_play:
            playMusic();
            break;
        case R.id.btn_pause:
            pauseMusic();
            break;
        case R.id.btn_stop:
            stopMusic();
            break;
    }
}

private void stopMusic() {
    mMediaPlayer.stop();
    try {
        //This is a blocking operation, avoid calling it on UI thread
        mMediaPlayer.prepare();
    } catch (IOException e) {
        Log.e("MediaPlayerActivity", "Prepare exception", e);
    }
}

private void pauseMusic() {
    mMediaPlayer.pause();

}

private void playMusic() {
    mMediaPlayer.start();
}

@Override
protected void onStop() {
    super.onStop();
    if (mMediaPlayer != null) {
        mMediaPlayer.release();
    }
}