Android学习笔记-Activity的生命周期

界面activity_main.xml

< RelativeLayout  xmlns:android = "http://schemas.android.com/apk/res/android"
    xmlns:tools = "http://schemas.android.com/tools"
    android:layout_width = "match_parent"
    android:layout_height = "match_parent"
    android:paddingBottom = "@dimen/activity_vertical_margin"
    android:paddingLeft = "@dimen/activity_horizontal_margin"
    android:paddingRight = "@dimen/activity_horizontal_margin"
    android:paddingTop = "@dimen/activity_vertical_margin"
    tools:context = "com.example.activity_05.MainActivity"  >

    < TextView
        android:id = "@+id/textView1"
        android:layout_width = "wrap_content"
        android:layout_height = "wrap_content"
        android:text = "@string/hello_world"  />

    < Button
        android:id = "@+id/button1"
        android:layout_width = "fill_parent"
        android:layout_height = "wrap_content"
        android:layout_below = "@+id/textView1"
        android:layout_marginTop = "22dp"
        android:text = "启动第二个Activity"  />

</ RelativeLayout >

界面second.xml

<? xml  version = "1.0"  encoding = "utf-8" ?>
< LinearLayout  xmlns:android = "http://schemas.android.com/apk/res/android"
    android:layout_width = "match_parent"
    android:layout_height = "match_parent"
    android:orientation = "vertical"  >

    < TextView
        android:id = "@+id/textView1"
        android:layout_width = "fill_parent"
        android:layout_height = "wrap_content"
        android:text = "This is the second activity"  />

</ LinearLayout >

MainActivity.java

package  com.example.activity_05;

import  android.support.v7.app.ActionBarActivity;
import  android.content.Intent;
import  android.os.Bundle;
import  android.view.Menu;
import  android.view.MenuItem;
import  android.view.View;
import  android.widget.Button;
import  android.view.View.OnClickListener;

public  class  MainActivity  extends  ActionBarActivity {
    private  Button button;

    @Override
    protected  void  onCreate(Bundle savedInstanceState) {
        super .onCreate(savedInstanceState);
        System.out.println( "MainActivity onCreate：第一次调用Activity的时候执行" );
        setContentView(R.layout.activity_main);
        button = (Button) findViewById(R.id.button1);
        button.setOnClickListener( new  OnClickListener() {

            @Override
            public  void  onClick(View v) {
                Intent intent =  new  Intent();
                intent.setClass(MainActivity. this , SecondActivity. class );
                MainActivity. this .startActivity(intent);
            }
        });
    }

    @Override
    protected  void  onResume() {
        System.out.println( "MainActivity onResume" );
        super .onResume();
    }

       //以上三个方法执行完毕之后这个Activity就可以使用了

    @Override
    protected  void  onStart() {
         System.out.println( "MainActivity onStart：Activity处于可见状态的时候调用" );
        super .onStart();
    }

    @Override
    protected  void  onRestart() {
        System.out.println( "MainActivity onRestart：Activity又可以得到用户焦点的时候调用" );
        System.out.println( "当从第二个Activity又回到第一个Activity时调用此方法" );
        System.out.println( "然后调用onResume方法就可以显示出来" );
        System.out.println( "然后调用第二个Activity的onStop、onDestroy。第二个Activity就被销毁掉了" );
        super .onRestart();
    }

    @Override
    protected  void  onPause() {
        System.out.println( "MainActivity onPause" );
        System.out.println( "如果在执行当前Activity的时候又启动了一个Activity就会调用当前Activity的此方法" );
        System.out.println( "然后依次调用新启动的Activity的onCreate、onStart、onResume" );
        System.out.println( "然后调用第一个Activity的onStop方法" );
        super .onPause();
    }

    @Override
    protected  void  onStop() {
        System.out.println( "MainActivity onStop" );
        //如果第二个Activity把第一个Activity完全遮挡住就调用这个函数
        super .onStop();
    }

    @Override
    protected  void  onDestroy() {
        System.out.println( "MainActivity onDestroy" );
        super .onDestroy();
    }
}

SecondActivity.java

package  com.example.activity_05;

import  android.app.Activity;
import  android.os.Bundle;

public  class  SecondActivity  extends  Activity {
    @Override
    protected  void  onCreate(Bundle savedInstanceState) {
        super .onCreate(savedInstanceState);
        setContentView(R.layout.second);
    }

    @Override
    protected  void  onStart() {
        System.out.println( "SecondActivity onStart" );
        super .onStart();
    }

    @Override
    protected  void  onRestart() {
        System.out.println( "SecondActivity onRestart" );
        super .onRestart();
    }

    @Override
    protected  void  onResume() {
        System.out.println( "SecondActivity onResume" );
        super .onResume();
    }

    @Override
    protected  void  onPause() {
        System.out.println( "SecondActivity onPause" );
        super .onPause();
    }

    @Override
    protected  void  onStop() {
        System.out.println( "SecondActivity onStop" );
        super .onStop();
    }

    @Override
    protected  void  onDestroy() {
        System.out.println( "SecondActivity onDestroy" );
        super .onDestroy();
    }
}

 

AndroidManifest.xml

< activity  android:name = ".SecondActivity"  android:label = "第二个Activity" />

 

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日志输出如下

每次显示栈顶Activity的内容

 

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