Activity的生命周期

我不想说话，我只要静静地看图，看十遍，写个Demo，然后什么都知道了。

Demo也是简单到不行：

package com.example.activitytest;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;

public class MainActivity extends Activity {

	@Override
	protected void onStart() {
		// TODO Auto-generated method stub
		super.onStart();
		System.out.println("---------------------onstart------------------------");
	}

	@Override
	protected void onRestart() {
		// TODO Auto-generated method stub
		super.onRestart();
		System.out.println("---------------------onrestart------------------------");
	}

	@Override
	protected void onResume() {
		// TODO Auto-generated method stub
		super.onResume();
		System.out.println("---------------------onresume------------------------");
	}

	@Override
	protected void onPause() {
		// TODO Auto-generated method stub
		super.onPause();
		System.out.println("---------------------onpause------------------------");
	}

	@Override
	protected void onStop() {
		// TODO Auto-generated method stub
		super.onStop();
		System.out.println("---------------------onstop------------------------");
	}

	@Override
	protected void onDestroy() {
		// TODO Auto-generated method stub
		super.onDestroy();
		System.out.println("---------------------ondestroy------------------------");
	}

	Button finish,startActivity;
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		finish = (Button) findViewById(R.id.button2);
		startActivity = (Button) findViewById(R.id.button1);
		
		System.out.println("-----------------------------oncreat-------------------------------");
		
		finish.setOnClickListener(new OnClickListener(){

			@Override
			public void onClick(View v) {
				// TODO Auto-generated method stub
				MainActivity.this.finish();
			}
			
		});
		startActivity.setOnClickListener(new OnClickListener(){

			@Override
			public void onClick(View v) {
				// TODO Auto-generated method stub
				Intent intent = new Intent(MainActivity.this,SecondActivity.class);
				startActivity(intent);
			}
			
		});
	}

	@Override
	public boolean onCreateOptionsMenu(Menu menu) {
		// Inflate the menu; this adds items to the action bar if it is present.
		getMenuInflater().inflate(R.menu.main, menu);
		return true;
	}

	@Override
	public boolean onOptionsItemSelected(MenuItem item) {
		// Handle action bar item clicks here. The action bar will
		// automatically handle clicks on the Home/Up button, so long
		// as you specify a parent activity in AndroidManifest.xml.
		int id = item.getItemId();
		if (id == R.id.action_settings) {
			return true;
		}
		return super.onOptionsItemSelected(item);
	}
}

运行会看出：

启动Activity：调用onCrea（），onStart（），onResume（）

跳转到另一个Activity，调用onPause（），onStop（）

按返回键返回到该Activity，调用onRestart（），onStart（），onResume（）

注销这个Activity，调用onPause（），onStop（），onDestroy（）