| Callback | Description | 
|---|---|
| onCreate() | This is the first callback and called when the activity is first created. | 
| onStart() | This callback is called when the activity becomes visible to the user. | 
| onResume() | This is called when the user starts interacting with the application. | 
| onPause() | The paused activity does not receive user input and cannot execute any code and called when the current activity is being paused and the previous activity is being resumed. | 
| onStop() | This callback is called when the activity is no longer visible. | 
| onDestroy() | This callback is called before the activity is destroyed by the system. | 
| onRestart() | This callback is called when the activity restarts after stopping it. | 
关键代码如下:
public class MainActivity extends Activity {
	private String msg="Android: ";
	/**
	 *  Called when the activity is first created.
	 */
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		Log.d(msg, "The onCreate() event");
	}
	/**
	 * Called when the activity is about to become visible.
	 */
	@Override
	protected void onStart() {
		// TODO Auto-generated method stub
		super.onStart();
		Log.d(msg, "The onStart() event");
	}
	
	/**
	 * Called when the activity has become visible.
	 */
	@Override
	protected void onResume() {
		// TODO Auto-generated method stub
		super.onResume();
		Log.d(msg, "The onResume() event");
	}
	
	/**
	 * Called when another activity is taking focus.
	 */
	@Override
	protected void onPause() {
		// TODO Auto-generated method stub
		super.onPause();
		Log.d(msg, "The onPause() event");
	}
	
	/**
	 * Called when the activity is no longer visible.
	 */
	@Override
	protected void onStop() {
		// TODO Auto-generated method stub
		super.onStop();
		Log.d(msg, "The onStop() event");
	}
	
	/**
	 * Called just before the activity is destroyed. 
	 */
	@Override
	protected void onDestroy() {
		// TODO Auto-generated method stub
		super.onDestroy();
		Log.d(msg, "The onDestroy() event");
	}
}
运行截图:
当Activity第一次打开时:

当启动另一个Activity时:

当关闭当前的Activity,返回到先前的Activity时:

当销毁当前Activity时:

原文:http://www.cnblogs.com/codemonkey-xsy/p/5671502.html