Lets put we 3 activates that may follow the stack A->B->C
How can I close A and keep B->C, but only if B opens C?
C is not always opened, but if it gets opened only then A should be removed, leaving the stack as B->C. Otherwise will remain as A->B.
I don’t see the possibility of using finish() in A, as it should be closed from B when opening C.
By the way A is a single instance with its own affinity.
Answer
Write an abstract BaseActivity class and implement a LocalBroadcastManager in it and register a BroadcastReceiver. Note that we have also introduced an abstract onFinishReceived method.
public abstract class BaseActivity extends AppCompatActivity {
private LocalBroadcastManager mLBM;
private final BroadcastReceiver receiver = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
onFinishReceived(intent.getStringExtra("activity"));
}
}
protected void onCreate(@Nullable Bundle savedInstanceState) {
...
mLBM = LocalBroadcastManager.getInstance(this);
IntentFilter filter = new IntentFilter();
filter.addAction(...);
mLBM.registerReceiver(receiver, filter);
}
protected void onDestroy() {
mLBM.unregisterReceiver(receiver);
mLBM = null;
}
abstract void onFinishReceived(String activity);
}
Then, extend all A, B and C Activities from the BaseActivity and override the onFinishReceived() method.
public class A extends BaseActivity {
void onFinishReceived(String activity) {
if (activity.equals("A") { // or "B" or "C"
finish();
}
}
}
}
Now, whenever you want to finish a specific activity use,
LocalBroadcastManager.getInstance(context)
.sendBroadcast(new Intent()
.setAction(...)
.putExtra("activity", "A") // or "B" or "C"
);
LocalBroadcastManager is now deprecated. It’s better if you can use something like RxJava. The idea is to use an asynchronous and event-based mechanism rather than going for a simple ugly solution like storing the Activity in a static variable.