WakeLock, PowerManager,uses-permission Android sample.
Main.java

public class Main extends Activity {
	    private SensorManager mSensorManager;
	    private PowerManager mPowerManager;
	    private WindowManager mWindowManager;
	    private WakeLock mWakeLock;
	    private Button button;
	    private TextView textView;

	    /** Called when the activity is first created. */
	    @Override
	    public void onCreate(Bundle savedInstanceState) {
	        super.onCreate(savedInstanceState);
try{
	        // Get an instance of the SensorManager
	        mSensorManager = (SensorManager) getSystemService(SENSOR_SERVICE);

	        // Get an instance of the PowerManager
	        mPowerManager = (PowerManager) getSystemService(POWER_SERVICE);

	        // Get an instance of the WindowManager
	        mWindowManager = (WindowManager) getSystemService(WINDOW_SERVICE);
	        mWindowManager.getDefaultDisplay();

	        // Create a bright wake lock
	        mWakeLock = mPowerManager.newWakeLock(PowerManager.SCREEN_BRIGHT_WAKE_LOCK, getClass()
	                .getName());

	        setContentView(R.layout.main);
	        textView = (TextView)findViewById(R.id.textView1);
	        button = (Button)findViewById(R.id.button1);
	        button.setOnClickListener(mButtonStopListener);
	       
	        
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
			Log.e("onCreate", e.getMessage());
		}
} // END onCreate
	    
	    View.OnClickListener mButtonStopListener = new OnClickListener() {
	    	public void onClick(View v) {
		        try {
					mWakeLock.release();
					textView.setText("mWakeLock.release()");
				} catch (Exception e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
					Log.e("onPause",e.getMessage());
				}
	    	
	    	}
	    };

	    @Override
	    protected void onResume() {
	        super.onResume();
	        /*
	         * when the activity is resumed, we acquire a wake-lock so that the
	         * screen stays on, since the user will likely not be fiddling with the
	         * screen or buttons.
	         */
	        
	        try {
				mWakeLock.acquire();
				textView.setText("mWakeLock.acquire()");
			} catch (Exception e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
				Log.e("onResume", e.getMessage());
			}

	    }

	    @Override
	    protected void onPause() {
	        super.onPause();

	        // and release our wake-lock
	        try {
				mWakeLock.release();
			} catch (Exception e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
				Log.e("onPause",e.getMessage());
			}
	    }
}

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="//schemas.android.com/apk/res/android"
      package="cz.okhelp.Main"
      android:versionCode="1"
      android:versionName="1.0">
    <uses-sdk android:minSdkVersion="7" />
    <uses-permission android:name="android.permission.HARDWARE_TEST"></uses-permission>
<uses-permission android:name="android.permission.VIBRATE"></uses-permission>

<uses-permission android:name="android.permission.WAKE_LOCK"></uses-permission>

    <application android:icon="@drawable/icon" android:label="@string/app_name">
        <activity android:name=".ScreenBrightnessActivity"
                  android:label="@string/app_name">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

    </application>
</manifest>

Call requires API level 16 (current min is 4): android
Change The SDK version in AndroidManifest.xml to higher

<uses-sdk android:minSdkVersion="4" />
// 
<uses-sdk android:minSdkVersion="8" />

Date difference in millisecond between two date, GregorianCalendar, Calendar, after(), befor(), getTimeInMillis().

public class HoriziontalScrollActivity extends Activity {
TextView txtV;
	Context cntx;
	
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        txtV = (TextView)findViewById(R.id.idLabel);
        cntx = this;
        StringBuilder strBuild = new StringBuilder();
        Calendar firstDate = new GregorianCalendar(2011, Calendar.DECEMBER, 31);
        Calendar secondDate = new GregorianCalendar(2012, Calendar.JANUARY, 1);

        
        Boolean bDetermine = firstDate.after(secondDate);            // false
        strBuild.append("Is firsDate after secondDate? " + bDetermine + "

");
        bDetermine = firstDate.before(secondDate);                   // true
        strBuild.append("Is firsDate before secondDate? " + bDetermine + "

");
        
        
        long differenceInMillisecond = 0L;
         differenceInMillisecond = secondDate.getTimeInMillis()-firstDate.getTimeInMillis();
         // second == 1000 millisecond
         long second = differenceInMillisecond / 1000L;
         strBuild.append("Difference between two dates is: " + second + "

");
        
         txtV.setText(strBuild);

    }
  
}

The source attachment does not contain the source for the file TextWatcher.class.
You can change the source attachment by clicking Change Attached Source below:

You have to add JDK src.zip path to dialog as on image below.
[caption id="attachment_1091" align="alignleft" width="282" caption="class file editor source not found Eclipse warning"][/caption]

Or go to Project > Properties > Java Build Path > Libraries
Expand JRE System Library. Expand rt.jar.
Select Source attachment and double click or Edit.
Type path the source code file (External File…) and press OK.

[caption id="attachment_1094" align="alignleft" width="300" caption="Java project build path"][/caption]

Or type path in Java JRE definition

[caption id="attachment_1105" align="alignleft" width="300" caption="Java JRE deifiniton path in Eclipse"][/caption]

How open String.class or others keywords definition with Eclipse.

Now if mouse move about keywords String or F3 on keywords and press button in yellow field will opened String.class

Update TextView from TimerTask, Handler, schedule, run, cancel TimerTask, Android example

public class TimerActivity extends Activity {
	TimerTask mTimerTask;
	final Handler handler = new Handler();
	Timer t = new Timer();	
TextView hTextView;
TableRow hTableRow;
Button hButton, hButtonStop;


private int nCounter = 0;
@Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        hTextView = (TextView)findViewById(R.id.idTextView);
        hButton = (Button)findViewById(R.id.idButton);
        hButton.setOnClickListener(mButtonStartListener);
        hButtonStop = (Button)findViewById(R.id.idButtonStop);
        hButtonStop.setOnClickListener(mButtonStopListener);

         
        
    } // end onCreate

View.OnClickListener mButtonStartListener = new OnClickListener() {
	public void onClick(View v) {
		doTimerTask();
    }
};



	
	View.OnClickListener mButtonStopListener = new OnClickListener() {
    	public void onClick(View v) {
    		stopTask();
    		
    	}
    };
    
    
    public void doTimerTask(){

    	mTimerTask = new TimerTask() {
    	        public void run() {
    	                handler.post(new Runnable() {
    	                        public void run() {
    	                        	nCounter++;
                                        // update TextView
    	                        	hTextView.setText("Timer: " + nCounter);

    	                        	Log.d("TIMER", "TimerTask run");
    	                        }
    	               });
    	        }};

            // public void schedule (TimerTask task, long delay, long period) 
    	    t.schedule(mTimerTask, 500, 3000);  // 

    	 }

    	  public void stopTask(){

    	   if(mTimerTask!=null){
    	      hTextView.setText("Timer canceled: " + nCounter);

    	      Log.d("TIMER", "timer canceled");
    	      mTimerTask.cancel();
    	 }
    
    }    
}