How to have a MouseMove event fire only if the mouse is hovered over an element for at least a specific amount of time?

Question

I want to display a JFrame when a user move the mouse pointer inside over a certain area of a JPanel with a little delay. I show the JFrame by attaching a MouseAdapter to the JPanel and overriding the MouseMove method.

addMouseListener(new MouseAdapter() {
  @Override
  public void mouseMoved(MouseEvent e) {
    Point p= e.getLocationOnScreen();
    //check if Point p is within the boundaries of a rectangle.          
    //show a JFrame
  }                
});

To obtain the delay I think that I should use something like a Thread by using sleep, with the condition that it must be interrupted if the mouse is moved out of the boundaries, but I'm not sure that this is the best approach. Currently, I only see on SO questions related to JavaScript. What's the best way to do it in Java?

Answer 1

Maybe a good solution is by using java.util.Timer.

addMouseListener(new MouseAdapter() {
 private int delay = 1000;//1 second
 private Timer timer = null;
 private int startTime =0;

  @Override
  public void mouseMoved(MouseEvent e) {
    Point p= e.getLocationOnScreen();
    boolean pointInArea=false;
    //check if Point p is within the boundaries of a rectangle.          
    if(pointInArea){
        //A JFrame is queued to be shown
        if(System.currentTimeMillis()-startTime>delay){
          //A JFrame has been already shown, then show a new one
          startTime = System.currentTimeMillis();
          timer = new Timer();                    
          timer.schedule(new TimerTask(){
              @Override
              public void run() {
                //LAUNCH JFrame
              }

          }, delay);                     
        }
     }
     else (!pointInArea && timer != null){
        timer.cancel();
        timer = null;                        
     }
  }                
});

Answer 2

You can use the mouseEntered and mouseExited events from the MouseAdapter class.

You can set a timer on the mouseEntered method and check if the time spent on the object is >= the designated time in the mouseExited method and if so perform the action.

For the scenario of mouse left at the same point, you can use the Timer with a delay of how many ever seconds you want and setup a handler at mouseExited to stop the timer if the pointer is exited before the designated time.