Guide to Object-oriented Programming With Java (Buffalo State University Version)
Chapter 17: Using WindowBuilder to Create GUI Applications
Using WindowBuilder to create a GUI application
There are many different controls that can be added to a frame or panel, including labels, textboxes, buttons, drop-down selectors, check boxes, radio buttons, and sliders, just to list a few.
This next figure shows the code for a ColorPicker program that allows the user to use sliders to determine the RGB (Red/Green/Blue) values for a color.
package edu.buffalostate.cis425.fa10.exercises.put-your-username-here;
/**
* File: ColorPicker.java
*
* Description: This app illustrates the use of the
* java.awt.Color class. It lets the user type red, green and
* blue (RGB) values into text fields, and displays the resulting
* color both as a font color and as a colored rectangle.
* This version of ColorPicker uses programmer defined IntFields
* which throw an out-of-range exception if the values input are
* not between 0 and 255. The only changes required occur in the
* declarations for the IntFields, in the init() method where the
* IntFields are instantiated, and in the actionPerformed() method
* the the getInt() method is used to retrieve their data.
*
* Assignment:
* 1) Run this program to see how it works
* 2) Modify this program so that it uses JSliders to
* select the range of colors. Arrange the JSliders
* so they are oriented horizontally and stacked using
* a grid layout:
*
* |-------- slider1 ----------|
* |-------- slider2 ----------|
* |-------- slider3 ----------|
*
* - See the example below (SliderExample) to get started
*/
/**
*
* @author Jim Gerland
*
*/
import javax.swing.*;
import java.awt.*;
import javax.swing.event.*;
public class ColorPicker extends JFrame implements ChangeListener {
private static final long serialVersionUID = 1L;
private int redIn, greenIn, blueIn;
// create the red slider
private final JSlider Red_slider = new JSlider(SwingConstants.HORIZONTAL,0,255,128);
// create the green slider
private final JSlider Green_slider = new JSlider(SwingConstants.HORIZONTAL,0,255,128);
// create the blue slider
private final JSlider Blue_slider = new JSlider(SwingConstants.HORIZONTAL,0,255,128);
private JPanel controls = new JPanel();
private Canvas canvas = new Canvas();
/**
* init() sets up the app's interface. A (default) border layout
* is used, with the controls at the north and the drawing canvas
* in the center.
*/
public ColorPicker() {
initControls();
getContentPane().add(controls, BorderLayout.NORTH);
canvas.setForeground(Color.LIGHT_GRAY);
getContentPane().add(canvas, "Center");
canvas.setBorder(BorderFactory.createTitledBorder("The Color Display"));
getContentPane().setBackground(Color.white);
setSize(300,250);
// register 'Exit upon closing' as a default close operation
setDefaultCloseOperation( EXIT_ON_CLOSE );
} // end ColorPicker()
/**
* initControls() arranges the app's control components in a separate
* JPanel, which is placed at the north border. The controls consist of
* three JTextFields into which the user can type RGB values.
*/
private void initControls() {
// HINT create 3 sliders instead of IntFields
controls.setLayout(new GridLayout(0,2));
JLabel R = new JLabel("Red:"); // adds the red slider label to the panel
R.setFont(new Font("Tahoma", Font.BOLD, 14));
R.setForeground(new Color(0, 0, 0));
R.setBackground(Color.BLUE);
R.setHorizontalAlignment(SwingConstants.RIGHT);
controls.add(R);
controls.add(Red_slider);//adds the red slider to the panel
JLabel G = new JLabel("Green:"); // adds the green slider label to the panel
G.setFont(new Font("Tahoma", Font.BOLD, 14));
G.setHorizontalAlignment(SwingConstants.RIGHT);
controls.add(G);
controls.add(Green_slider); // adds the green slider to the panel
JLabel B = new JLabel("Blue:"); // adds the blue slider label to the panel
B.setFont(new Font("Tahoma", Font.BOLD, 14));
B.setHorizontalAlignment(SwingConstants.RIGHT);
controls.add(B);
controls.add(Blue_slider);// adds the blue slider to the panel
redIn = Red_slider.getValue();
greenIn = Green_slider.getValue();
blueIn = Blue_slider.getValue();
Red_slider.addChangeListener(this);
Green_slider.addChangeListener(this);
Blue_slider.addChangeListener(this);
} // end initControls()
public void stateChanged(ChangeEvent e) {
JSlider value = (JSlider)e.getSource();
if (value == Red_slider) {
redIn = value.getValue();
canvas.setColor(new Color(redIn,greenIn,blueIn));
} else if(value == Green_slider) {
greenIn = value.getValue();
canvas.setColor(new Color(redIn,greenIn,blueIn));
} else if(value == Blue_slider) {
blueIn = value.getValue();
canvas.setColor(new Color(redIn,greenIn,blueIn));
}
canvas.repaint();
} // end stateChanaged()
public static void main(String args[]) {
ColorPicker c = new ColorPicker();
c.setVisible(true);
} // end main()
} // end ColorPicker
Figure 17-1: Sample ColorPicker.java
Code
Figure 17-2: Sample ColorPicker.java
Application
Let's get started with a Conversion program