What is the difference between the paint() and repaint() methods

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The paint() method supports painting via a Graphics object. The repaint() method is used to causepaint() to be invoked by the AWT painting thread.

In Java, specifically in graphical user interface (GUI) programming using AWT or Swing, the paint() and repaint() methods serve different purposes.

  1. paint() method:
    • The paint() method is part of the Component class (or its subclasses like JComponent) and is responsible for actually rendering the visual representation of the component.
    • When a component needs to be drawn or updated on the screen, the paint() method is called automatically by the system.
    • You override the paint() method in your custom component to define how it should be visually represented.
    java
    public void paint(Graphics g) {
    // Drawing logic goes here
    }
  2. repaint() method:
    • The repaint() method is used to request a redrawing of a component.
    • When you call repaint(), it doesn’t immediately invoke the paint() method. Instead, it schedules a call to the update() method and then to paint().
    • The system decides when to execute the actual painting operation, and it may combine multiple repaint() requests into a single update for efficiency.
    java
    component.repaint();

In summary, paint() is responsible for the actual drawing logic, and repaint() is used to request a redraw of a component. The system manages when the actual painting occurs, and it may optimize the process by combining multiple repaint requests.