How to Control Android back stack

Question

Lets say I have

A->B->C->D->E

In android back stack. I want to be able to get back to one of the following:

A->B->C
A->B
A
<         


        

Answer 1

Use FLAG_ACTIVITY_CLEAR_TOP flag.

Intent a = new Intent(this, A.class);
a.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(a);

Answer 2

Suppose you are using Intent to move to another activity

Intent i = new Intent(A.this,B.class);
startActivity(i);

this code will take you to the 'B' Activity and when you press Back button it will again take you to the 'A' Activity . If you dont want to go back to activity 'A' you can use....

Intent i = new Intent(A.this,B.class);
i.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
i.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TASK);
startActivity(i);

For more information about Back Stack in Android Follow this link : http://developer.android.com/guide/components/tasks-and-back-stack.html

Answer 3

Actually , to go "up" to the activity of your choice, you should use the "up" navigation as used on the action bar:

/** used to handle the "up" button on the action bar, to go to the defined top activity as written on the manifest */
public static void goUpToTopActivity(final Activity currentActivity) {
    final Intent intent = NavUtils.getParentActivityIntent(currentActivity);
    intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP | Intent.FLAG_ACTIVITY_SINGLE_TOP);
    NavUtils.navigateUpTo(currentActivity, intent);
}

in order to use it, you must set on the manifest to which activity this function should use (or you could of course set it yourself by changing the code) :

if you use actionBarSherlock, for each activity that you wish to let to go up, use:

<meta-data
    android:name="android.support.PARENT_ACTIVITY"
    android:value="com.your_app.activities.MainActivity" />

if you use the android framework (if your minSdk version is API 16 and above), use the "parentActivityName" attribute.

Answer 4

Using the image and information from the official developers page on Android tasks and back stack you can see that of all other ways to launch an Activity you can ensure such behavior only using the FLAG_ACTIVITY_CLEAR_TOP in your Intent flags.

Your regular back button proceeds as:

But when you specify this flag, you get a behavior like you need, as given by an example at this source:

consider a task consisting of the activities: A, B, C, D. If D calls startActivity() with an Intent that resolves to the component of activity B, then C and D will be finished and B receive the given Intent, resulting in the stack now being: A, B.