//: c13:Separation.java
// From Thinking in Java, 2nd Edition
// Available at http://www.BruceEckel.com
// (c) Bruce Eckel 1999
// Copyright notice in Copyright.txt
// Separating GUI logic and business objects
// <applet code=Separation
// width=300 height=150> </applet>
import javax.swing.*;
import java.awt.*;
import javax.swing.event.*;
import java.awt.event.*;
import java.applet.*;

class BusinessLogic {
  private int modifier;
  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 {
  JTextField 
    t = new JTextField(15),
    mod = new JTextField(15);
  BusinessLogic bl = new BusinessLogic(2);
  JButton
    calc1 = new JButton("Calculation 1"),
    calc2 = new JButton("Calculation 2");
  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);
  }
  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 static void main(String[] args) {
    JApplet applet = new Separation();
    JFrame frame = new JFrame("Separation");
    frame.addWindowListener(
      new WindowAdapter() {
        public void windowClosing(WindowEvent e){
          System.exit(0);
        }
      });
    frame.getContentPane().add(applet);
    frame.setSize(300, 150);
    applet.init();
    applet.start();
    frame.setVisible(true);
  }
} ///:~