Java: Graphics2D

The javax.swing.Graphics2D class of Java 2 supports many more graphics operations than the Graphics class. For example,

Graphics2D additional features

Aliasing
Shapes
Affine transformations (scaling, rotation, skewing)
[list many others, this is only a rough beginning]

Graphics objects are Graphics2D objects

The Graphics object that is passed to paintComponent is really a Graphice2D object in Java 2, so it may quickly be downcast to Graphics2D to make additional methods available. For example

public void paintComponent(Graphics g) {
    super.paintComponent(g);
    Graphics2D g2 = (Graphics2D)g;
    // Use g2 for all following operations 
    g2.drawLine(...);