android – 为什么从后台线程中解除ProgressDialog时没有抛出异常？

/**
 * Dismiss this dialog,removing it from the screen. This method can be
 * invoked safely from any thread.  Note that you should not override this
 * method to do cleanup when the dialog is dismissed,instead implement
 * that in {@link #onStop}.
 */
public void dismiss() {
    if (Thread.currentThread() != mUiThread) {
        mHandler.post(mDismissAction);
    } else {
        mDismissAction.run();
    }
}