Investigation of FLAG_ACTIVITY_NEW_TASK, FLAG_ACTIVITY_CLEAR_TOP and launchMode in Activity to realize the behavior of clearing the top of the stack

<activity
    android:name=".export.LiveChannelListActivity"
    android:configChanges="orientation|keyboardHidden|screenSize"
    android:launchMode="singleTask"
    android:screenOrientation="landscape" />

public static void start(Context context) {
    Intent starter = new Intent(context, LiveChannelListActivity.class);
    starter.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK|Intent.FLAG_ACTIVITY_CLEAR_TOP);
    context.startActivity(starter);
}

1. FLAG_ACTIVITY_NEW_TASK: 

Call several times to open several Activity instances

2. FLAG_ACTIVITY_NEW_TASK|FLAG_ACTIVITY_CLEAR_TOP

Each call opens to create a new Activity instance, and destroys the old one

 

3. FLAG_ACTIVITY_NEW_TASK  设置launcheMode = singleTask

Repeated calls will no longer create a new Activity instance. The onNewIntent callback of an Activity has been created. If you want to reuse an existing instance, you should use this method.

 

4. FLAG_ACTIVITY_NEW_TASK|FLAG_ACTIVITY_CLEAR_TOP  设置launcheMode = singleTask

Same as 3. That is to say, if launcheMode = singleTask is set, it doesn't matter if FLAG_ACTIVITY_CLEAR_TOP is set or not.

 

5. If FLAG_ACTIVITY_NEW_TASK is not set, Activity cannot be started from Service,  to be verified