Android启动模式

发表于 2018-08-06 阅读次数：

Android: Understanding Activity launch mode

‘standard’ and ‘singleTop’ can instantiate multiple activity instances and the instance will stay in the same task.

For ‘singleTask’ or ‘singleInstance’, the activity class uses the singleton pattern, and that instance will be the root activity of a new task. Let’s examine each value:

the weird launch mode

https://stackoverflow.com/questions/9363200/android-singletask-singletop-and-home-button
The behaviour of activity back stack becomes quit weird when define main activity with singleTask at the same time:

    <activity android:name=".MainActivity"
        android:launchMode="singleTask">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
    
What even worse is there is no clear explanation in the official dev guide regarding to this special use case. Some sections related to this topic are even self-contradictory.

Try using launchMode="standard" on your MainActivity A, and launchMode="singleTask" on your Activity B, which will give the expect behaviour you described.

自学笔记：Activity的启动模式:FLAG_ACTIVITY_CLEAR_TOP和FLAG_ACTIVITY_REORDER_TO_FRONT

// A, B, C 和 D ==> A, B
Intent intent = new Intent(this, B.class);
intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(intent);

// add below code , B will be reused.
intent.addFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP);

// A，B，C和D ==> A,C,D,B，
Intent intent = new Intent(this, MainActivity.class);
intent.addFlags(Intent.FLAG_ACTIVITY_REORDER_TO_FRONT);
startActivity(intent);

深入讲解Android中Activity launchMode - 技术小黑屋

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