Java for Android

Johann Mitlöhner 2012

Software Installation

1. Sun/Oracle JDK 1.6
   • download JDK 1.6
   • bash jdk-6u31-linux-i586.bin
   • pico .bashrc, add export JAVA_HOME=$HOME/jdk1.6.0_31, exit, new terminal
2. Android SDK
   • Download the current Android SDK for Linux i386
   • or r21
   • tar zxf android-sdk_r22-linux.tgz
   • android-sdk-linux/tools/android
   • install Tools and Android 4.0.3
3. IntelliJ Idea
   • download free community edition
   • tar zxf ideaIC-11.0.2.tar.gz
   • idea-IC-111.277/bin/idea.sh
   • create sample Project
   • select Java SDK (JSDK): point to home directory (/srv/ai/localhost/home/.../jdk1.6.0_31)
   • level 1.6
   • select Android SDK 4.0.3 (/srv/ai/localhost/home/.../android-sdk-linux)
   • run sample app in emulator

Android Concepts

• Activities
  • public class MyActivity extends Activity { ... }
  • life cycle managed by system (callbacks onCreate(), onPause(), onResume(), onDestroy())
  • Manifest android:launchMode=["multiple" | "singleTop" | "singleTask" | "singleInstance"]
  • Button Home: activity to background, Back: activity destroyed
• Layouts
  • LinearLayout, TableLayout, ...
  • TextView, EditText, ...
  • findViewById()
• Options
  • MenuInflater() from XML file
  • onCreateOptionsMenu()
  • onOptionsItemSelected()
• Preferences
  • SharedPreferences
  • PreferenceActivity
  • startActivity(new Intent(this, Preferences.class))
• Permissions
  • AndroidManifest.xml after </application>
  • <uses-permission android:name="android.permission.INTERNET" />
• Misc
  • OnClickListener() vs. OnLongClickListener() --- double touch UI not recommended

     
        x.setOnLongClickListener(new OnLongClickListener() { 
            public boolean onLongClick(View v) {
                // do some work
                return true;
            }
        });
      

Sample applications

HTTP transfer and user preferences

• res/layout: main.xml
• res/menu: actionbar.xml
• res/xml: preferences.xml
• src/com.example: MyActivity.java
• src/com.example: Preferences.java

Animation using Mouse interaction, canvas drawing, threads

• src/net.mitloehner.flocki: MyActivity.java
• src/net.mitloehner.flocki: DrawView.java
• src/net.mitloehner.flocki: DrawThread.java
• src/net.mitloehner.flocki: Flocki.java

Board Game using TableLayout and ImageView

• src/net.mitloehner.noughts: MyActivity.java

More at

• android.com
• stackoverflow.com