With this tutorial we are going to show 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 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
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:
package com.javacodegeeks.snippets.desktop;
import java.awt.Color;
import java.awt.Container;
import java.awt.event.MouseWheelEvent;
import java.awt.event.MouseWheelListener;
import javax.swing.JFrame;
public class MouseWheelListenerExample extends JFrame {
private static final Color colorArray[] = {Color.BLACK, Color.BLUE, Color.CYAN, Color.DARK_GRAY, Color.GRAY, Color.GREEN,
Color.LIGHT_GRAY, Color.MAGENTA, Color.ORANGE, Color.PINK, Color.RED, Color.WHITE, Color.YELLOW};
public MouseWheelListenerExample() {
super();
final Container cPane = getContentPane();
MouseWheelListener mouseWheelListener = new MouseWheelListener() {
int cnt;
private static final int up_color = 1;
private static final int down_col = 2;
@Override
public void mouseWheelMoved(MouseWheelEvent event) {
int stps = event.getWheelRotation();
int dir = (Math.abs(stps) > 0) ? up_color : down_col;
changeBackground(dir);
}
private void changeBackground(int dir) {
cPane.setBackground(colorArray[cnt]);
if (dir == up_color) {
cnt++;
} else {
--cnt;
}
if (cnt == colorArray.length) {
cnt = 0;
} else if (cnt < 0) {
cnt = colorArray.length - 1;
}
}
};
cPane.addMouseWheelListener(mouseWheelListener);
}
public static void main(String args[]) {
JFrame jFrame = new MouseWheelListenerExample();
jFrame.setSize(600, 400);
jFrame.setVisible(true);
}
}This was an example no how to use MouseWheelListener in Java.
did you even test your code?
int dir = (Math.abs(stps) > 0) ? up_color : down_col;
Do you notice something? Something which has to do with Math.abs?