A JList is a subclass of JComponent class and it can be used to display a list of objects that allows the user to select one or more items. A JList can generate a ListSelectiionListener interface and need to implement the abstract method valueChanged(). A JToolTip class is used to display a text or a tip of the component, we can set a tooltip text for each item of a list by implementing the getToolTipText() method of JToolTip class.
Example
import java.awt.*; import java.awt.event.*; import javax.swing.*; import java.util.*; public class JListTooltipTest extends JFrame { private Vector vector; public JListTooltipTest() { setTitle("JListTooltip Test"); setLayout(new FlowLayout()); vector = new Vector(); for (int i=1; i < 15; i++) { vector.addElement("Item #" + i); } final JList list = new JList(vector) { public String getToolTipText(MouseEvent me) { int index = locationToIndex(me.getPoint()); if (index > -1) { String item = (String) getModel().getElementAt(index); return "Tooltip for " + item; } return null; } }; list.setToolTipText(""); add(new JScrollPane(list)); setSize(375, 250); setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); setLocationRelativeTo(null); setVisible(true); } public static void main(String[] args) { new JListTooltipTest(); } }