Factory Method Pattern in Java : Factory Pattern « Design Pattern « Java

1. Java
2. Design Pattern
3. Factory Pattern

Factory Method Pattern in Java

//[C] 2002 Sun Microsystems, Inc.---
import java.awt.Container;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.io.Serializable;

import javax.swing.BoxLayout;
import javax.swing.JButton;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextArea;
import javax.swing.JTextField;


public class RunFactoryMethodPattern {
    public static void main(String [] arguments){
        System.out.println("Example for the FactoryMethod pattern");
        System.out.println();
        
        System.out.println("Creating a Contact object");
        System.out.println();
        Contact someone = new Contact();
        
        System.out.println("Creating a GUI editor for the Contact");
        System.out.println();
        System.out.println("The GUI defined in the EditorGui class is a truly generic editor.");
        System.out.println("It accepts an argument of type ItemEditor, and delegates");
        System.out.println(" all editing tasks to its ItemEditor and the associated GUI.");
        System.out.println(" The getEditor() Factory Method is used to obtain the ItemEditor");
        System.out.println(" for the example.");
        System.out.println();
        System.out.println("Notice that the editor in the top portion of the GUI is,");
        System.out.println(" in fact, returned by the ItemEditor belonging to the");
        System.out.println(" Contact class, and has appropriate fields for that class.");
        
        EditorGui runner = new EditorGui(someone.getEditor());
        runner.createGui();
    }
}
class EditorGui implements ActionListener{
    private JFrame mainFrame;
    private JTextArea display;
    private JButton update, exit;
    private JPanel controlPanel, displayPanel, editorPanel;
    private ItemEditor editor;
    
    public EditorGui(ItemEditor edit){
        editor = edit;
    }
    
    public void createGui(){
        mainFrame = new JFrame("Factory Pattern Example");
        Container content = mainFrame.getContentPane();
        content.setLayout(new BoxLayout(content, BoxLayout.Y_AXIS));
        
        editorPanel = new JPanel();
        editorPanel.add(editor.getGUI());
        content.add(editorPanel);
        
        displayPanel = new JPanel();
        display = new JTextArea(10, 40);
        display.setEditable(false);
        displayPanel.add(display);
        content.add(displayPanel);
        
        controlPanel = new JPanel();
        update = new JButton("Update Item");
        exit = new JButton("Exit");
        controlPanel.add(update);
        controlPanel.add(exit);
        content.add(controlPanel);
        
        update.addActionListener(this);
        exit.addActionListener(this);
        
        mainFrame.addWindowListener(new WindowCloseManager());
        mainFrame.pack();
        mainFrame.setVisible(true);
    }
    
    
    public void actionPerformed(ActionEvent evt){
        Object originator = evt.getSource();
        if (originator == update){
            updateItem();
        }
        else if (originator == exit){
            exitApplication();
        }
    }
    
    private class WindowCloseManager extends WindowAdapter{
        public void windowClosing(WindowEvent evt){
            exitApplication();
        }
    }
    
    private void updateItem(){
        editor.commitChanges();
        display.setText(editor.toString());
    }
    
    private void exitApplication(){
        System.exit(0);
    }
}

class Contact implements Editable, Serializable {
    private String name;
    private String relationship;

    public ItemEditor getEditor() {
        return new ContactEditor();
    }
    
    private class ContactEditor implements ItemEditor, Serializable {
        private transient JPanel panel;
        private transient JTextField nameField;
        private transient JTextField relationField;
        
        public JComponent getGUI() {
            if (panel == null) {
                panel = new JPanel();
                nameField = new JTextField(name);
                relationField = new JTextField(relationship);
                panel.setLayout(new GridLayout(2,2));
                panel.add(new JLabel("Name:"));
                panel.add(nameField);
                panel.add(new JLabel("Relationship:"));
                panel.add(relationField);
            } else {
                nameField.setText(name);
                relationField.setText(relationship);
            }
            return panel;
        }
        
        public void commitChanges() {
            if (panel != null) {
                name = nameField.getText();
                relationship = relationField.getText();
            }
        }
        
        public String toString(){
            return "\nContact:\n" +
                "    Name: " + name + "\n" +
                "    Relationship: " + relationship;
        }
    }
}

interface Editable {
    public ItemEditor getEditor();
}

interface ItemEditor {
    public JComponent getGUI();
    public void commitChanges();
}


           
       

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