按钮点击后如何等待执行操作？

Question

As a beginner in Android programming, I don't really master the use of the threads and the Handler() function. After clicking on a button, I'd like to call a first method startProjection() then wait a few seconds before call a second method stopProjection ().

By reading some topics about the question, I built this code, able to perform the first call but not the second :

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    // some code

    // start projection
    Button startButton = (Button) findViewById(R.id.startButton);
    startButton.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View v) {
            startProjection();

            Handler handler = new Handler();
            handler.postDelayed(new Runnable() {
                public void run() {
                    stopProjection();
                }
            }, 7000);
        }
    });

The Build Gradle works correctly but when I finally click on the Button nothing happens. It seems that the handler doesn't work correctly. Is there anyway to perform these actions in the same onClick() method ?

EDIT : Previously the two methods were called separately buy using two buttons (and it works !), but I really want to use a single button.

Answer 1

I just want to check if you have any specific reason to have stopProjection() function in a seperate thread. May be the following might work fine :

startProjection();
Thread.sleep(7000);
stopProjection();