import java.awt.ScrollPane;
...
private ScrollPane scroller;
...
// ScrollPane.SCROLLBARS_AS_NEEDED is the default
// ScrollPane.SCROLLBARS_ALWAYS
// ScrollPane.SCROLLBARS_NEVER (rather pointless)
scroller = new ScrollPane( ScrollPane.SCROLLBARS_ALWAYS );

// controls how fast you scroll with the wheelmouse.
scroller.getVAdjustable().setUnitIncrement( 16 );

// add the contents you want scolled, usually a Panel or Canvas
scroller.add ( aPanel );