Android SDK Samples as a Photo Gallery

Log.e println needs a message error.
E/AndroidRuntime(330): FATAL EXCEPTION: main
java.lang.RuntimeException: Unable to start activity ComponentInfo{b.paint/b.paint.MainActivity}: java.lang.NullPointerException: println needs a message

Try this code:

		// Error
                String s = null;
		Log.e("bla", s); // !!! error Log.e println needs a message error.
                // OK
		String s = null;
		Log.e("bla", s+""); // OK 

Problem: erroneous entry of id

<RadioButton android:id="idRadio"
                android:text="My radio button"/>

Solution: @+id/

<RadioButton android:id="@+id/idRadio"
                android:text="My radio button"/>

How start certain Activity if user clicked to ListView item
Start Activity from list – launches other activities from list - latest variant!!!!

public class Main extends Activity {
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        
        try {
        setContentView(R.layout.main);
        
			ListView mlistView = (ListView) findViewById(R.id.idListView);
			mlistView.setAdapter(new ArrayAdapter<String>(this,
			        android.R.layout.simple_list_item_1, 
			        new String[] {"Game", "Help", "Home site"}));
    
        mlistView.setOnItemClickListener(new OnItemClickListener() {
            public void onItemClick(AdapterView<?> parent, View view,
                int position, long id) {
              // When clicked, show a toast with the TextView text Game, Help, Home
              Toast.makeText(getApplicationContext(), ((TextView) view).getText(),
                  Toast.LENGTH_SHORT).show();
              String sText = ((TextView) view).getText().toString();
              Intent intent = null;
              if(sText.equals("Game"))
              intent = new Intent(getBaseContext(),
						Game.class);
              //else if(sText.equals("Help")) ..........

              if(intent != null)
				startActivity(intent);              
            }
          });
        } catch (Exception e) {
        	// TODO Auto-generated catch block
        	e.printStackTrace();
        }
    
    }
}

Game class Game.java game.xml
You have to add class Game to AndroidManifest.xml

        <activity android:name=".Game" android:label="GameLabel">
        </activity>

package cz.okhelp.listview;

import android.app.Activity;
import android.os.Bundle;

public class Game extends Activity{
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        
        // you have to create game.xml 
        setContentView(R.layout.game);
    }
}

If you using GoogleAdMobAdsSdk-4.0.4.jar in your project and set android:targetSdkVersion="17" in AndroidManifest.xml , ads will not visible on emulator with Android 4.0.3 or 4.1.
You have to set as android:targetSdkVersion="17"

<uses-sdk android:minSdkVersion="4" 
        android:targetSdkVersion="17" />

Update project.properties file - row with target to 17:

# Project target.
target=android-17

public class MainActivity extends Activity {
	
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(new SampleView(this));
	}

	private static class SampleView extends View {

		// CONSTRUCTOR
		public SampleView(Context context) {
			super(context);
			setFocusable(true);

		}
		@Override
		protected void onDraw(Canvas canvas) {
			Paint paint = new Paint();
			
			canvas.drawColor(Color.GREEN);
            
            Bitmap b = Bitmap.createBitmap(200, 200, Bitmap.Config.ALPHA_8);
             paint.setColor(Color.BLUE);
            
           Canvas c = new Canvas(b);
           c.drawRect(0, 0, 200, 200, paint);
           
           canvas.drawBitmap(b, 10,10, paint);
		}

	}
}