Default value for resultCode when activity finishes

Question

This might be a basic question, but I hoping to get some clarity.

What I am trying to do: 1) Starting an activity with a requestCode, and handling two operations in onActivityResult, one using RESULT_OK, another using RESULT_CANCELLED. I explicitly state each of them.

The issue is even when I close the activity just using back button and not setting any result the Activity in the back stack receives RESULT_CANCELLED.

Going through the source code I see that RESULT_CANCELLED is the default value for the resultcode and that the resultcode is always sent back.

Am i reading this right and is this what happens all the time? or am I doing something wrong in my application?

Source: https://github.com/android/platform_frameworks_base/blob/master/core/java/android/app/Activity.java

Answer 1

When your starting Activity is restarting, the onActivityResult(..) method of this Activity is called before the onResume() method is called. check Doc for Activity

And the default resultCode is RESULT_CANCELLED.

You must explicitly call setResult(int) in the started Activity to change the value of resultCode.

And that's why it's important to check resultCode == RESULT_OK in the onActivityResult method. Because the onActivityResult can be called even if you have not called startActivityForResult.

Which can be confusing, but that's the default behaviour.

  @Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    // Check which request we're responding to
    if (requestCode == YOUR_REQUEST) {
        // Make sure the request was successful
        if (resultCode == RESULT_OK) {
            // so some work
        }
    }
}

Answer 2

您必须始终通过setResult（）方法提供结果代码