【移动应用开发技术】Android学习笔记-Activity的生命周期

【移动应用开发技术】Android学习笔记-Activity的生命周期

界面activity_main.xml<RelativeLayout

xmlns:android="/apk/res/android"

xmlns:tools="/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="/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.javapackage

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.javapackage

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(