Android学习笔记-Activity的生命周期

界面activity_main.xml

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< 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

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<? 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

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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

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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

1	< 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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