Android Activity生命周期举例说明（图文）

同学电话面试提及到Activity生命周期的详细说明，现整理如下：

转载请标明姓名及出处：大飞_Rflyee - http://blog.youkuaiyun.com/rflyee/article/details/9055547

必备知识背景：（详见官网：

1、Activity生命周期常见的七种方法：onCreate()、onStart()、onRestart()、onResume()、onPause()、onStop()、onDestroy()

2、调用顺序规则（官网）

下面以“Activity A转到B，再返回A”为例，说明各方法调用顺序：

情况一、B将A完全遮挡

调用顺序：

A：onCreate() - onStart() - onResume() - onPause()

B：onCreate() - onStart() - onResume()

A：onStop()

B：onPause()

A：onRestart() - onStart() - onResume()

B ：onStop() - onDestroy()

实例：

启动应用，第一个activity

logCat视图如下：

启动第二个activity，将第一个完全覆盖

logCat视图如下：

按下返回键，重现回到第一个activity之后logCat视图如下：

附源代码（仅供参考），转载请标明作者及出处：大飞_Rflyee - http://blog.youkuaiyun.com/rflyee/article/details/9055547

MainActivity.java

package com.example.myactivitylife;

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

public class MainActivity extends Activity {
	private static final String TAG = "--activityLife--";
	private Button bt1 = null;
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		
		bt1 = (Button)findViewById(R.id.button1);
		bt1.setOnClickListener(new OnClickListener() {
			
			@Override
			public void onClick(View v) {
				
				Intent intent = new Intent(MainActivity.this,SecindActivity.class);
				startActivity(intent);
				
			}
		});
		
		Log.i(TAG, "onCreate_first");
	}
	
	@Override
	protected void onStart() {
		super.onStart();
		Log.i(TAG, "onStart_first");
	}
	
	@Override
	public void onRestart(){
		super.onRestart();
		Log.i(TAG, "onRestart_first");
	}

	@Override
	public void onResume(){
		super.onResume();
		Log.i(TAG, "onResume_first");
	}
	@Override
	public void onPause(){
		super.onPause();
		Log.i(TAG,"onPause_first");
	}
	@Override
	public void onStop(){
		super.onStop();
		Log.i(TAG, "onStop_first");
	}
	@Override
	public void onDestroy(){
		super.onDestroy();
		Log.i(TAG, "onDestroy_first");
	}

	@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;
	}

}

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=".MainActivity" >

    <TextView
        android:id="@+id/textview1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="this is the first activity!" />
    <Button 
        android:id="@+id/button1"
        android:layout_below="@id/textview1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Next Activity"/>

</RelativeLayout>

SecondActivity.java

package com.example.myactivitylife;

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

public class SecindActivity extends Activity{
	private final String tag = "--dialog--";
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.second);
		
		Log.i(tag, "onCreate_second");
	}

	@Override
	protected void onDestroy() {
		super.onDestroy();
		Log.i(tag, "onDestroy_second");
	}

	@Override
	protected void onPause() {
		super.onPause();
		Log.i(tag, "onPause_second");
	}

	@Override
	protected void onRestart() {
		super.onRestart();
		Log.i(tag, "onRestart_second");
	}

	@Override
	protected void onResume() {
		super.onResume();
		Log.i(tag, "onResume_second");
	}

	@Override
	protected void onStart() {
		super.onStart();
		Log.i(tag, "onStart_second");
	}

	@Override
	protected void onStop() {
		super.onStop();
		Log.i(tag, "onStop_second");
	}
	
}

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/next_textview"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="this the second activity!"/>

</LinearLayout>

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.myactivitylife"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="10"
        android:targetSdkVersion="17" />

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name="com.example.myactivitylife.MainActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <activity 
            android:name=".SecindActivity">
            
        </activity>
    </application>

</manifest>

情况二、
B不能将A完全遮挡

调用顺序：

A：onCreate() - onStart() - onResume() - onPause()

B：onCreate() - onStart() - onResume() - onPause()

A：onResume()

B ：onStop() - onDestroy()

实例效果图：

启动A - 启动B -返回A整个过程的logCat视图：

附源代码（仅供参考），

只需将情况一中的AndroidManifest.xml稍作改动即可（将第二个activity的Theme声明为Theme.Dialog）

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.myactivitylife"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="10"
        android:targetSdkVersion="17" />

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name="com.example.myactivitylife.MainActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <activity 
            android:name=".SecindActivity"
            android:theme="@android:style/Theme.Dialog">
            
        </activity>
    </application>

</manifest>

转载请标明作者及出处：大飞_Rflyee - http://blog.youkuaiyun.com/rflyee/article/details/9055547