With this tutorial we are going to sow you how to use a MouseWheelListener in Java. This event listener is particularly useful when you want to add extra user friendly functionality in your application. For example if you want, for example, the user to change the value of a specific item, you can allow him to do that using the wheel of the mouse.
In short in order to work with MouseWheelListener in Java you can:
- Create a new class that implements
MouseWheelListener. - Override the
mouseWheelMovedmethod, which will fire up every time the user moves the mouse wheel. - Use
addMouseWheelListenermethod to bundle a specific component with the listener. Every time the cursor is in the area of the component and the wheel is moved the listener will handle the event as we said before.
Let’s see the code snippets that follow:
001 002 003 004 005 006 007 008 009 010 011 012 013 014 015 016 017 018 019 020 021 022 023 024 025 026 027 028 029 030 031 032 033 034 035 036 037 038 039 040 041 042 043 044 045 046 047 048 049 050 051 052 053 054 055 056 057 058 059 060 061 062 063 064 065 066 067 068 069 070 071 072 073 074 075 076 077 078 079 080 081 082 083 084 085 086 087 088 089 090 091 092 093 094 095 096 097 098 099 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 | package com.javacodegeeks.snippets.desktop;import java.awt.BorderLayout;import java.awt.Dimension;import java.awt.event.MouseWheelEvent;import java.awt.event.MouseWheelListener;import javax.swing.BorderFactory;import javax.swing.JComponent;import javax.swing.JFrame;import javax.swing.JPanel;import javax.swing.JScrollPane;import javax.swing.JTextArea;public class WheelE extends JPanel implements MouseWheelListener { JTextArea jTextArea; JScrollPane scPane; final static String nl = "n"; public WheelE() { super(new BorderLayout()); jTextArea = new JTextArea(); jTextArea.setEditable(false); scPane = new JScrollPane(jTextArea); scPane.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS); scPane.setPreferredSize(new Dimension(420, 350)); add(scPane, BorderLayout.CENTER); jTextArea.append(""); jTextArea.addMouseWheelListener(this); setPreferredSize(new Dimension(500, 500)); setBorder(BorderFactory.createEmptyBorder(40, 40, 40, 40)); } @Override public void mouseWheelMoved(MouseWheelEvent event) { String print; int steps = event.getWheelRotation(); if (steps < 0) {print = "Wheel moved UP " + -steps + " step(s)" + nl; } else {print = "Wheel moved DOWN " + steps + " step(s)" + nl; } if (event.getScrollType() == MouseWheelEvent.WHEEL_UNIT_SCROLL) {print += "Type: WHEEL_UNIT_SCROLL" + nl;print += "Amount: " + event.getScrollAmount() + " unit increments per step" + nl;print += "Units to scroll: " + event.getUnitsToScroll() + " unit increments" + nl;print += "Vertical unit increment: " + scPane.getVerticalScrollBar().getUnitIncrement(1) + " pixels" + nl; } else { //scroll type == MouseWheelEvent.WHEEL_BLOCK_SCROLLprint += "Type: WHEEL_BLOCK_SCROLL" + nl;print += "Vertical block increment: " + scPane.getVerticalScrollBar().getBlockIncrement(1) + " pixels" + nl; } saySomething(print, event); } void saySomething(String eventDescription, MouseWheelEvent e) { jTextArea.append(e.getComponent().getClass().getName() + ": " + eventDescription); jTextArea.setCaretPosition(jTextArea.getDocument().getLength()); } private static void dispGUI() { JFrame.setDefaultLookAndFeelDecorated(true); JFrame frame = new JFrame("MouseWheelEventExample"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); JComponent newContentPane = new WheelE(); newContentPane.setOpaque(true); frame.setContentPane(newContentPane); frame.pack(); frame.setVisible(true); } public static void main(String[] args) { javax.swing.SwingUtilities.invokeLater(new Runnable() {@Overridepublic void run() { dispGUI();} }); }} |
This was an example on how to work MouseWheelListener in a Java Desktop application.
