How to set a tooltip text for each item of a JList in Java?

In this article, we will learn to set a tooltip text for each item of a JList in Java. Tooltips give meaningful information as users hover over UI components. Swing's JList does not support tooltips on a per-item basis, so it will involve some customization.

What is JList?

A JList is a subclass of the 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 ListSelectionListener interface and needs to implement the abstract method valueChanged().

Syntax

The following is the syntax for JList initialization:

JList<String> list = new JList<>(model);

JToolTip class

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.

Setting a Tooltip Text for a JList

The following is the step-by-step for setting a tooltip text for each item of a JList in Java:

Class Declaration and Imports

The javax.swing.* provides Swing components (JToolTip, JFrame, etc.) while the java.awt.* provides AWT classes (Color, layout managers), and the class extends JFrame to create a window.

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.util.*;
public class JListTooltipTest extends JFrame {

Instance Variable & Constructor

Declares a Vector to hold the data that will populate the JList. The constructor sets the JFrame window titled "JListTooltip Test" and uses FlowLayout as the layout manager.

private Vector vector;
public JListTooltipTest() {
    setTitle("JListTooltip Test");
    setLayout(new FlowLayout());

JList Implementation

Creates an anonymous subclass of JList that overrides getToolTipText().

final JList list = new JList(vector) {
    public String getToolTipText(MouseEvent me) {

JList Configuration

Sets an empty initial tooltip, wraps the JList in a JScrollPane, and adds the scroll pane to the JFrame.

list.setToolTipText("");
add(new JScrollPane(list));

Main Method

The main method launches the application by creating an object of JListTooltipTest.

public static void main(String[] args) {
    new JListTooltipTest();
}

Example

Below is an example to set a tooltip text for each item of a JList in Java:

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();
   }
}

Output