The back key cannot be captured after Android pops out of Dialog

First, the demand

During the Android development process, the back key cannot be captured after ejecting the dialog, and no response is clicked.

Second, the solution

Cause: When the dialog pops up, the activity loses focus and dialog gets the current focus.

Workaround: In dialog, you can increase the listening of key events for dialog by calling the Setonkeylistener () method.

private void Createdialog () {
    Alertdialog.builder Builder = new Alertdialog.builder (this);
    Builder.settitle (getString (r.string.acq_select_hint));

    Builder.setpositivebutton (GetString (R.string.dialog_cancel), (Dialog, which), Oncancelclicked (dialog));

    Builder.setcancelable (FALSE);
   
    Builder.setonkeylistener (Dialog, KeyCode, event), {
        if (keycode = = Keyevent.keycode_back) {
            oncancelclicked (Dialog);
        }
        return false;
    });
    Builder.create (). Show ();
}

private void Oncancelclicked (Dialoginterface dialog) {
    Setresult (100);
    Finish ();
    Dialog.dismiss ();
}

The back key cannot be captured after Android pops out of Dialog