Command pattern in Java 3
/*
The Design Patterns Java Companion
Copyright (C) 1998, by James W. Cooper
IBM Thomas J. Watson Research Center
*/
import java.awt.Button;
import java.awt.Color;
import java.awt.FileDialog;
import java.awt.Frame;
import java.awt.Menu;
import java.awt.MenuBar;
import java.awt.MenuItem;
import java.awt.Panel;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
interface Command {
public void Execute();
}
public class ExtrnCommand extends Frame implements ActionListener {
Menu mnuFile;
fileOpenCommand mnuOpen;
fileExitCommand mnuExit;
btnRedCommand btnRed;
Panel p;
Frame fr;
//-----------------------------------------
public ExtrnCommand() {
super("Frame with external commands");
fr = this; //save frame object
MenuBar mbar = new MenuBar();
setMenuBar(mbar);
mnuFile = new Menu("File", true);
mbar.add(mnuFile);
mnuOpen = new fileOpenCommand("Open...", this);
mnuFile.add(mnuOpen);
mnuExit = new fileExitCommand("Exit");
mnuFile.add(mnuExit);
mnuOpen.addActionListener(this);
mnuExit.addActionListener(this);
p = new Panel();
add(p);
btnRed = new btnRedCommand("Red", p);
p.add(btnRed);
btnRed.addActionListener(this);
setBounds(100, 100, 200, 100);
setVisible(true);
}
//-----------------------------------------
public void actionPerformed(ActionEvent e) {
Command obj = (Command) e.getSource();
obj.Execute();
}
//-----------------------------------------
static public void main(String argv[]) {
new ExtrnCommand();
}
}
//==========================================
class btnRedCommand extends Button implements Command {
Panel p;
public btnRedCommand(String caption, Panel pnl) {
super(caption);
p = pnl;
}
public void Execute() {
p.setBackground(Color.red);
}
}
//------------------------------------------
class fileOpenCommand extends MenuItem implements Command {
Frame fr;
public fileOpenCommand(String caption, Frame frm) {
super(caption);
fr = frm;
}
public void Execute() {
FileDialog fDlg = new FileDialog(fr, "Open file");
fDlg.show();
}
}
//-------------------------------------------
class fileExitCommand extends MenuItem implements Command {
public fileExitCommand(String caption) {
super(caption);
}
public void Execute() {
System.exit(0);
}
}
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