android生命周期的例子

第四课，对android中Activity生命周期的讲解。

package com.myclover.life;

import android.app.Activity;
import android.app.AlertDialog;
import android.app.Dialog;
import android.content.DialogInterface;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;

/**
 * 测试Activity的生命周期
 * @author myclover
 * </br>
 * 执行流程如下：
 * 在应用在启动时先执行onCreate，在界面可见但是不可点击时执行onStart，在界面可见并可操作时执行onResume，
 * 当界面再次不可点击时执行onPause，在界面不可见时执行onStop，如果调用了finish()，那么接着会执行onDestroy
 * 
 * 该测试程序执行的结果为：
 * execute first onCreate---->execute first onStart---->execute first onResume---->(跳转)
 * execute first onPause---->execute second onCreate---->execute second onStart---->
 * execute second onResume---->execute first onStop---->execute first onDestroy---->(返回)
 * execute second onPause---->execute first onCreate---->execute first onStart---->
 * execute first onResume----> execute second onStop---->execute second onDestroy
 */
public class LifeDemoActivity extends Activity {
	
	private static final String TAG = "LifeDemoActivity";
	
	@Override
    public void onCreate(Bundle savedInstanceState) {
		Log.i(TAG, "execute first onCreate!");
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        Button redirectBtn = (Button)findViewById(R.id.redirectBtn);
        Button toThirdBtn = (Button)findViewById(R.id.toThirdBtn);
        redirectBtn.setOnClickListener(new View.OnClickListener() {
			@Override
			public void onClick(View v) {
			//弹出确认选择框
			Dialog dialog =	new AlertDialog.Builder(LifeDemoActivity.this)
				//设置弹出框标题
				.setTitle(R.string.title)
				//设置弹出框提示信息
				.setMessage(R.string.message)
				//设置确定按钮
				.setPositiveButton(R.string.sure, new DialogInterface.OnClickListener() {
					//点击确定按钮执行的方法
					@Override
					public void onClick(DialogInterface dialog, int which) {
						Intent intent = new Intent();
						//设置Activity的跳转
						intent.setClass(LifeDemoActivity.this, SecondActivity.class);
						//启动新Activity
						LifeDemoActivity.this.startActivity(intent);
						//销毁当前Activity
						LifeDemoActivity.this.finish();
						Log.i(TAG, "redirect to second activity!");
					}
				})
				//设置取消按钮
				.setNegativeButton(R.string.cancel, new DialogInterface.OnClickListener() {
					//点击取消按钮执行的方法
					@Override
					public void onClick(DialogInterface dialog, int which) {
						Log.i(TAG, "click cancel !");
					}
				}).create();
			dialog.show();
			}
		});
        
        toThirdBtn.setOnClickListener(new OnClickListener() {
			@Override
			public void onClick(View v) {
				Intent intent = new Intent();
				//设置Activity的跳转
				intent.setClass(LifeDemoActivity.this, ThirdActivity.class);
				//启动新Activity
				LifeDemoActivity.this.startActivity(intent);
				//销毁当前Activity
//				LifeDemoActivity.this.finish();
				Log.i(TAG, "redirect to third activity!");
			}
		});
        
    }

	@Override
	protected void onStart() {
		Log.i(TAG, "execute first onStart!");
		super.onStart();
	}

	@Override
	protected void onRestart() {
		Log.i(TAG, "execute first onRestart!");
		super.onRestart();
	}

	@Override
	protected void onResume() {
		Log.i(TAG, "execute first onResume!");
		super.onResume();
	}

	@Override
	protected void onPause() {
		Log.i(TAG, "execute first onPause!");
		super.onPause();
	}

	@Override
	protected void onStop() {
		Log.i(TAG, "execute first onStop!");
		super.onStop();
	}

	@Override
	protected void onDestroy() {
		Log.i(TAG, "execute first onDestroy!");
		super.onDestroy();
	}
	
}