StopOn500

main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical"
    android:gravity="center"
    android:clickable="true"
    android:id="@+id/wholeScreen">

    <TextView
        android:id="@+id/countView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:gravity="center"
        android:textSize="100dip"
        />
    
</LinearLayout>

StopOn500Activity.java

package com.cguild.stopon500;

import java.util.concurrent.atomic.AtomicInteger;

import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.TextView;
import android.widget.Toast;

public class StopOn500Activity extends Activity {
	
	private static final String TAG                = StopOn500Activity.class.getSimpleName();
	private static final int    TARGET             = 500;
	private static final int    INITIAL_DIFFICULTY = 25;
	private static final int    DIFFICULTY_CHANGE  = 5;
	private static final int    HARDEST_DIFFICULTY = 10;
	private static final int    GOOD_DELTA         = 10;
	
	private AtomicInteger mCount       = new AtomicInteger();
	private int           mDifficulty  = INITIAL_DIFFICULTY;
	private Thread        mTimerThread = null;
	private TextView      mCountView   = null;
	private boolean       mWon         = false;
    
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        
        setContentView(R.layout.main);
        mCountView = (TextView) findViewById(R.id.countView);
    }
    
    @Override
    protected void onResume() {
    	super.onResume();
    	
    	mDifficulty = INITIAL_DIFFICULTY;
    	startGame();
    	
    	findViewById(R.id.wholeScreen).setOnClickListener(new OnClickListener() {
			@Override
			public void onClick(View v) {
				mTimerThread.interrupt();
				try {
					mTimerThread.join();
				} catch (InterruptedException e) {
					e.printStackTrace();
				}
				updateCountUi();
				
				final int delta = Math.abs(TARGET-mCount.get());
				gameFinished(delta);
			}
		});
    }
    
    @Override
    protected void onPause() {
    	super.onPause();
    	
    	mTimerThread.interrupt();
    	mTimerThread = null;
    }
    
    private void updateCountUi() {
    	mCountView.setText(mCount.get()+"");
    }
    
    private void startGame() {
    	if (mTimerThread != null && !mTimerThread.isInterrupted()) {
    		Log.w(TAG, "Timer thread is already running!");
    	}
    	
    	mCount.set(0);
    	mTimerThread = new TimerThread(new Handler());
    	mTimerThread.start();
    }
    
    private void gameFinished(final int delta) {
    	if (delta <= GOOD_DELTA) {
			mDifficulty -= DIFFICULTY_CHANGE;
			if (mDifficulty < HARDEST_DIFFICULTY) {
				mWon = true;
				mCountView.setText("You win!");
			} else {
				Toast.makeText(this, "Good!", Toast.LENGTH_SHORT).show();
				startGame();
			}
    	} else {
    		Toast.makeText(this, "Bad :(", Toast.LENGTH_SHORT).show();
			startGame();
    	}
    }
    
    private class CountUpdater implements Runnable {
    	@Override
    	public void run() {
    		if (!mWon) {
    			updateCountUi();
    		}
    	}
    }
    
    private class TimerThread extends Thread {
    	private final Handler mHandler;
    	
    	public TimerThread(final Handler handler) {
    		mHandler = handler;
    	}
    	
    	@Override
    	public void run() {
    		while (!isInterrupted()) { 
    			mCount.incrementAndGet();
    			mHandler.post(new CountUpdater());
	    		try {
	    			Thread.sleep(mDifficulty);
	    		} catch (InterruptedException e) {
	    			Thread.currentThread().interrupt();
	    			return;
	    		}
    		}
    	}
    }
    
}