更改方向后重新启动应用程序（Oncreate）

我的应用程序中有一个计时器，如果在所有4个方向上都改变了方向，我想重新启动计时器。我尝试通过添加Onconfigurationchanged（）方法来实现，但它没有调用并为我工作。

MainActivity.class

 @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        Log.i("tag","oncreate changed");
        setContentView(R.layout.activity_main);
        timer = (AppCompatEditText)findViewById(R.id.editText);
        totalHoursText = (TextView)findViewById(R.id.totalhoursText);
        startButton = (Button)findViewById(R.id.button);
        stopButton = (Button)findViewById(R.id.button1);
        totalHoursText.setVisibility(View.INVISIBLE);

        startButton.setOnClickListener(this);
        stopButton.setOnClickListener(this);
        handler = new Handler();


    }


    @Override
    public void onConfigurationChanged(Configuration newConfig) {
        super.onConfigurationChanged(newConfig);
        Log.i("tag", "orientation changed");

        int orientation = newConfig.orientation;
        switch (orientation) {
            case Configuration.ORIENTATION_LANDSCAPE:
                Log.i("tag", "orientation changed landscape");
                // Checks the orientation of the screen
                if (newConfig.orientation == Configuration.ORIENTATION_LANDSCAPE) {
                    Toast.makeText(this, "landscape", Toast.LENGTH_SHORT).show();
                } else if (newConfig.orientation == Configuration.ORIENTATION_PORTRAIT) {
                    Toast.makeText(this, "portrait", Toast.LENGTH_SHORT).show();
                }
        }
    }


    @Override
    public void onClick(View v) {
        switch (v.getId()){
            case R.id.button :
                Time time = new Time();
                time.setToNow();
                flag=true;
                startTime = time.toMillis(false);
                handler.postDelayed(updateTimerThread,0);
                totalHoursText.setVisibility(View.INVISIBLE);

                break;

            case R.id.button1:
                timer.setText("00:00");
                flag=false ;
                handler.removeCallbacksAndMessages(updateTimerThread);
                break;
        }

    }


    private Runnable updateTimerThread = new Runnable() {

        String str;
        public void run() {


            if(flag) {
                Time time = new Time();
                time.setToNow();

                timeInMilliseconds = time.toMillis(false) - startTime;
                updatedTime = timeSwapBuff + timeInMilliseconds;


                int secs = (int) (updatedTime / 1000);
                int mins = secs / 60;
                secs = secs % 60;
                int milliseconds = (int) (updatedTime % 1000);


                int sec = (int) (updatedTime / 1000) % 60;
                int min = (int) ((updatedTime / (1000 * 60)) % 60);
                int hr = (int) ((updatedTime / (1000 * 60 * 60)) % 24);

                 str = "" + String.format("%02d", hr) + ":"
                        + String.format("%02d", min) + ":"
                        + String.format("%02d", sec);


                timer.setText("" + String.format("%02d", hr) + ":"
                        + String.format("%02d", min) + ":"
                        + String.format("%02d", sec));

                handler.postDelayed(this, 0);
            }
        else{
                totalHoursText.setVisibility(View.VISIBLE);
                totalHoursText.setText(str);
            }
        }

    };

请帮我提出建议或代码段。