Activity launchMode四分之二 ----singleTop

A Activity程序清單

package com.demo.activitylifecycle;


import android.app.Activity;
import android.content.Intent;
import android.content.res.Configuration;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;


public class AActivity extends Activity {


private static int mIndex = 1;


@Override
protected void onCreate(Bundle savedInstanceState) { // 創建Activity時被回調
super.onCreate(savedInstanceState);
setContentView(R.layout.layout_a);


Log.i("ActivityLog", "A taskId: " + getTaskId() + "， A create："
+ mIndex);
++mIndex;
Button _AButton = (Button) findViewById(R.id.button1);
Button _BButton = (Button) findViewById(R.id.button2);
// 按鈕點擊事件，點擊AActivity啓動AActivity
_AButton.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
Intent _intent = new Intent(AActivity.this, AActivity.class);
startActivity(_intent);
}
});
// 按鈕點擊事件，點擊BActivity啓動BActivity
_BButton.setOnClickListener(new OnClickListener() {


@Override
public void onClick(View v) {
Intent _intent = new Intent(AActivity.this, BActivity.class);
startActivity(_intent);
}
});


}


@Override
protected void onNewIntent(Intent intent) {
super.onNewIntent(intent);
Log.i("ActivityLog",  " B onNewIntent");
}
@Override
protected void onDestroy() {
super.onDestroy();
Log.i("ActivityLog", "A taskId: " + getTaskId() + "， A destroy："
+ mIndex);
}
}

B Activity程序清單

package com.demo.activitylifecycle;


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


public class BActivity extends Activity {
private static int mIndex = 1;


@Override
protected void onCreate(Bundle savedInstanceState) { // 創建Activity時被回調
super.onCreate(savedInstanceState);
setContentView(R.layout.layout_a);


Log.i("ActivityLog", "B taskId: " + getTaskId() + "，B create：" + mIndex);
++mIndex;
Button _AButton = (Button) findViewById(R.id.button1);
Button _BButton = (Button) findViewById(R.id.button2);
// 按鈕點擊事件，點擊AActivity啓動AActivity
_AButton.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
Intent _intent = new Intent(BActivity.this, AActivity.class);
startActivity(_intent);
}
});
// 按鈕點擊事件，點擊BActivity啓動BActivity
_BButton.setOnClickListener(new OnClickListener() {


@Override
public void onClick(View v) {
Intent _intent = new Intent(BActivity.this, BActivity.class);
startActivity(_intent);
}
});


TextView textView = (TextView) findViewById(R.id.textView);
textView.setText("B Activity");
}


@Override
protected void onNewIntent(Intent intent) {
super.onNewIntent(intent);
Log.i("ActivityLog",  " B onNewIntent");
}


@Override
protected void onDestroy() {
super.onDestroy();
Log.i("ActivityLog", "B taskId: " + getTaskId() + "，B destroy："
+ mIndex);


}


}

A Activity和B Activity佈局程序清單

<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"
    tools:context="${relativePackage}.${activityClass}" >


    <TextView
        android:id="@+id/textView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="A Activity" />


    <Button
        android:id="@+id/button1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_below="@+id/textView"
        android:layout_marginTop="16dp"
        android:text="AActivity" />


    <Button
        android:id="@+id/button2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignRight="@+id/button1"
        android:layout_below="@+id/button1"
        android:layout_marginTop="14dp"
        android:text="BActivity" />


</RelativeLayout>

Manifest程序清單

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


    <uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="19" />


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


                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <activity
            android:name=".BActivity"
            android:label="BActivity"

          android:launchMode="singleTop">
        </activity>
    </application>


</manifest>

小結：1、A Activity 和 B Activity 界面佈局相同，A Activity啓動A Activity，B Activity啓動 B Activity 。 

                 重載onCreate、onNewIntent、onDestroy

                  A Activity 的launchMode是standard（默認）

                   B Activity 的launchMode都是singleTop

            2、創建Activity時打印log-----TaskID以及實例次數

                 Log.i("ActivityLog", "B taskId: " + getTaskId() + "，B create：" + mIndex);

            3、啓動A，再啓動B，啓動B，再啓動A，再啓動B

            4、A Activity  launchMode是standard，每啓動一次Activity都生成一個Activity的實例，生成幾個實例按back鍵幾次才能返回到主界面

                  B Activity  launchMode是singleTop，當B Activity的實例在棧頂時，再啓動 B Activity不再重新生成實例，而是調用onNewIntent，按back鍵一次即可返回