戻るボタンを押すまでにダイアログを表示したかったのですが、以下のコードでは実行されず、FragmentDialog が表示されません。前もって感謝します。
  //BackPress
      public void onBackPressed() {
          TestDialogFragment test= new TestDialogFragment();
          test.newInstace();
            // Showing Alert Message
          Log.d("Video Backpressed", "sdfdf");
      }
TestDialogFragment
public static class TestDialogFragment extends DialogFragment {
    public static DialogFragment newInstace() {
        DialogFragment dialogFragment = new TestDialogFragment();
        return dialogFragment;
    }
    @Override
    public Dialog onCreateDialog(Bundle savedInstanceState) {
        AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
        builder.setTitle("TestDialogFragment");
        builder.setView(getContentView());
        Dialog dialog = builder.create();
        return dialog;
    }
    private View getContentView() {
        LayoutInflater inflater = getActivity().getLayoutInflater();
        return inflater.inflate(R.layout.dialog_fragment, null);
    }
    }