Prevent same activity to be started multiple times

Question

There are a lot of questions related to back stack management, but none really satisfied me. The closer I found is that one but it looks like an ugly workaround to me.

When clicking on a button in activity A, I'm launching an activity B with startActivityForResult(), expecting a simple A -> B back stack. But if you spam the button fast enough, you end up with two intents being fired and thus two activities stacked A -> B -> B.

I tried to use FLAG_ACTIVITY_SINGLE_TOP flag to prevent the second B activity from being created but it didn't change anything:

This is the button listener in activity A:

btn.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View view) {
        Intent intent = new Intent(getApplicationContext(), ActivityB.class);
        intent.setFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP);
        startActivityForResult(intent, REQUEST_CODE);
    }
});

And logs clearly states that onCreate() in invoked twice (instead of the expected onNewIntent):

btn.onClick()

activityB.onCreate()

btn.onClick()

activityB.onCreate()

My activity must not be singleTask nor singleInstance, they should just be part of the back stack as any regular activity. Any clearance would be much appreciated!

Answer 1

Your problem is two activity started by you button click spamming.

In a simple way set boolean field to prevent starting two activities.

Example:

boolean isClicked;
button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if(!isClicked){
                 isClicked = true;
                 //start activity here.
                }
            }
        });

In your onPause() set the boolean field false.