【移动应用开发技术】Android Activity生命周期

【移动应用开发技术】AndroidActivity生命周期

Android—Activity生命周期一、图解

二、概念分析

当一个活动被创建时，调用onCreate()

方法当一个活动能被用户看到（即可见）时，调用onStart()

方法当一个活动可获取用户焦点时，调用onResume()

方法所以打开一个活动时，会先后执行onCreate()->onStart()->onResume三个方法

当一个活动不能获取用户焦点时（此时另一个活动进入前台），调用onPause()

方法当一个活动不可见（即被其他活动完全覆盖）时，调用onStop()

方法当我们准备启动另一个新的活动覆盖当前活动时时，会依次调用当前活动类的

onPause()

->

onStop()

方法

当我们再次启动该活动，该活动由后台转到前台运行时，会依次调用该活动类的onRestart()->onStart()->onResume()三个方法

当我们退出程序，或调用finish()

方法时，则依次调用

onPause()

->

onStop()

->

onDestroy()

方法

三、例子说明

//FirstActivity.javapackage

mars.activity05;

import

android.app.Activity;import

android.content.Intent;import

android.os.Bundle;import

android.view.View;import

android.view.View.OnClickListener;import

android.widget.Button;

public

class

FirstActivity

extends

Activity

{/**

Called

when

the

activity

is

first

created.

*/private

Button

myButton;

@Overridepublic

void

onCreate(Bundle

savedInstanceState)

{System.out.println("FirstActivity

>

onCreate

");super.onCreate(savedInstanceState);setContentView(R.layout.main);myButton

=

(Button)

findViewById(R.id.myButton);myButton.setOnClickListener(new

ButtonListener());}

@Overrideprotected

void

onDestroy()

{//

TODO

Auto-generated

method

stubSystem.out.println("FirstAcvity

>onDestory");super.onDestroy();}

@Overrideprotected

void

onPause()

{//

TODO

Auto-generated

method

stubSystem.out.println("FirstAcvity

>onPause");super.onPause();}

@Overrideprotected

void

onRestart()

{//

TODO

Auto-generated

method

stubSystem.out.println("FirstAcvity

>onRestart");super.onRestart();}

@Overrideprotected

void

onResume()

{//

TODO

Auto-generated

method

stubSystem.out.println("FirstAcvity

>onResume");super.onResume();}

@Overrideprotected

void

onStart()

{//

TODO

Auto-generated

method

stubSystem.out.println("FirstAcvity

>onStart");super.onStart();}

@Overrideprotected

void

onStop()

{//

TODO

Auto-generated

method

stubSystem.out.println("FirstAcvity

>onStop");super.onStop();}

class

ButtonListener

implements

OnClickListener

{

@Overridepublic

void

onClick(View

v)

{//

TODO

Auto-generated

method

stubIntent

intent

=

new

Intent();intent.setClass(FirstActivity.this,

SecondActivity.class);intent.putExtra("extra_data",

"Hello

I'm

FirstActivity!");FirstActivity.this.startActivity(intent);}

}

}

//mian.xml<?xml

version="1.0"

encoding="utf-8"?><LinearLayout

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

android:orientation="vertical"

android:layout_width="fill_parent"

android:layout_height="fill_parent"

><TextView

android:layout_width="fill_parent"

android:layout_height="wrap_content"

android:text="@string/hello"

/><Buttonandroid:id="@+id/myButton"android:layout_width="fill_parent"android:layout_height="wrap_content"android:text="@string/first_button"/></LinearLayout>

//SecondActivity.java

package

mars.activity05;

import

android.app.Activity;import

android.content.Intent;import

android.os.Bundle;import

android.view.View;import

android.view.View.OnClickListener;import

android.widget.Button;import

android.widget.TextView;

public

class

SecondActivity

extends

Activity{

private

Button

secondButton;TextView

text

=

null;String

str

=

null;@Overrideprotected

void

onCreate(Bundle

savedInstanceState)

{System.out.println("SecondActivity>onCreate");//

TODO

Auto-generated

method

stubsuper.onCreate(savedInstanceState);setContentView(R.layout.second);secondButton

=

(Button)findViewById(R.id.secondButton);secondButton.setOnClickListener(new

ButtonListener());text

=

(TextView)

findViewById

(R.id.text);Intent

intent

=

getIntent();str

=

intent.getStringExtra("extra_data");text.setText(str);}

@Overrideprotected

void

onDestroy()

{//

TODO

Auto-generated

method

stubSystem.out.println("SecondActivity>onDestory");super.onDestroy();}

@Overrideprotected

void

onPause()

{//

TODO

Auto-generated

method

stubSystem.out.println("SecondActivity>onPause");super.onPause();}

@Overrideprotected

void

onRestart()

{//

TODO

Auto-generated

method

stubSystem.out.println("SecondActivity>onRestart");super.onRestart();}

@Overrideprotected

void

onResume()

{//

TODO

Auto-generated

method

stubSystem.out.println("SecondActivity>onResume");super.onResume();}

@Overrideprotected

void

onStart()

{//

TODO

Auto-generated

method

stubSystem.out.println("SecondActivity>onStart");super.onStart();}

@Overrideprotected

void

onStop()

{//

TODO

Auto-generated

method

stubSystem.out.println("SecondActivity>onStop");super.onStop();}

class

ButtonListener

implements

OnClickListener{

@Overridepublic

void

onClick(View

v)

{//

TODO

Auto-generated

method

stubIntent

intent

=

new

Intent();intent.setClass(SecondActivity.this,

FirstActivity.class);SecondActivity.this.startActivity(intent);}}}

//second.xml<?xml

version="1.0"

encoding="utf-8"?><LinearLayout

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

android:orientation="vertical"

android:layout_width="fill_parent"

android:layout_height="wrap_content"

>

<TextView

android:id="@+id/text"

android:layout_width="fill_parent"

android:layout_height="wrap_content"

android:text="@string/second_button"

></TextView>

<Button

android:id="@+id/secondButton"

android:layout_width="fill_parent"

android:layout_height="wrap_content"

android:text="@string/second_button"

/></LinearLayout>

//AndroidManifest.xml

中注册

SecondActivity

<activity

android:name=".SecondActivity"

android:label="SecondActivity"

android:theme="@android:style/Theme.Dialog"/>

//string.xml

<?