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| Separating GUI logic and business objects |
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// : c14:Separation.java
// Separating GUI logic and business objects.
// <applet code=Separation width=250 height=150></applet>
// From 'Thinking in Java, 3rd ed.' (c) Bruce Eckel 2002
// www.BruceEckel.com. See copyright notice in CopyRight.txt.
import java.awt.Container;
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JApplet;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.event.DocumentEvent;
import javax.swing.event.DocumentListener;
class BusinessLogic {
private int modifier;
public BusinessLogic(int mod) {
modifier = mod;
}
public void setModifier(int mod) {
modifier = mod;
}
public int getModifier() {
return modifier;
}
// Some business operations:
public int calculation1(int arg) {
return arg * modifier;
}
public int calculation2(int arg) {
return arg + modifier;
}
}
public class Separation extends JApplet {
private JTextField t = new JTextField(15), mod = new JTextField(15);
private JButton calc1 = new JButton("Calculation 1"), calc2 = new JButton(
"Calculation 2");
private BusinessLogic bl = new BusinessLogic(2);
public static int getValue(JTextField tf) {
try {
return Integer.parseInt(tf.getText());
} catch (NumberFormatException e) {
return 0;
}
}
class Calc1L implements ActionListener {
public void actionPerformed(ActionEvent e) {
t.setText(Integer.toString(bl.calculation1(getValue(t))));
}
}
class Calc2L implements ActionListener {
public void actionPerformed(ActionEvent e) {
t.setText(Integer.toString(bl.calculation2(getValue(t))));
}
}
// If you want something to happen whenever
// a JTextField changes, add this listener:
class ModL implements DocumentListener {
public void changedUpdate(DocumentEvent e) {
}
public void insertUpdate(DocumentEvent e) {
bl.setModifier(getValue(mod));
}
public void removeUpdate(DocumentEvent e) {
bl.setModifier(getValue(mod));
}
}
public void init() {
Container cp = getContentPane();
cp.setLayout(new FlowLayout());
cp.add(t);
calc1.addActionListener(new Calc1L());
calc2.addActionListener(new Calc2L());
JPanel p1 = new JPanel();
p1.add(calc1);
p1.add(calc2);
cp.add(p1);
mod.getDocument().addDocumentListener(new ModL());
JPanel p2 = new JPanel();
p2.add(new JLabel("Modifier:"));
p2.add(mod);
cp.add(p2);
}
public static void main(String[] args) {
run(new Separation(), 250, 100);
}
public static void run(JApplet applet, int width, int height) {
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(applet);
frame.setSize(width, height);
applet.init();
applet.start();
frame.setVisible(true);
}
} ///:~
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