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Simple Editor
Posted on: July 22, 2006 at 12:00 AM
This simple text editor uses a JTextArea with Actions to implement the menu items.

Java: Example - Simple Editor

This simple text editor uses a JTextArea with Actions to implement the menu items. Actions are a good way to implement ActionListeners.

  • Actions can be used with most buttons, including toobox buttons and menu items, text fields, etc.
  • They can be shared so that all controls which do the same thing can share an Action.
  • Actions can be dis-/enabled, and they will then dis-/enable all corresponding controls.
  • They can be used to set icons, tooltip text, accelerator and mnemonic keys.

 

 

 

 

 

 

 

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// editor/NutPad.java -- A very simple text editor -- Fred Swartz - 2004-08
// Illustrates use of AbstractActions for menus.

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.io.*;

public class NutPad extends JFrame {
    //-- Components 
    private JTextArea mEditArea;
    private JFileChooser mFileChooser = new JFileChooser(".");
    
    //-- Actions
    private Action mOpenAction;
    private Action mSaveAction;
    private Action mExitAction;
    
    //===================================================================== main
    public static void main(String[] args) {
        new NutPad().setVisible(true);
    }//end main
    
    //============================================================== constructor
    public NutPad() {
        createActions();
        this.setContentPane(new contentPanel());
        this.setJMenuBar(createMenuBar());
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        this.setTitle("NutPad");
        this.pack();
    }//end constructor

    ///////////////////////////////////////////////////////// class contentPanel
    private class contentPanel extends JPanel {        
        //========================================================== constructor
        contentPanel() {
            //-- Create components.
            mEditArea = new JTextArea(15, 80);
                mEditArea.setBorder(BorderFactory.createEmptyBorder(2,2,2,2));
                mEditArea.setFont(new Font("monospaced", Font.PLAIN, 14));
            JScrollPane scrollingText = new JScrollPane(mEditArea);
            
            //-- Do layout
            this.setLayout(new BorderLayout());
            this.add(scrollingText, BorderLayout.CENTER);
        }//end constructor
    }//end class contentPanel
    
    //============================================================ createMenuBar
    /** Utility function to create a menubar. */
    private JMenuBar createMenuBar() {
        JMenuBar menuBar = new JMenuBar();
            JMenu fileMenu = menuBar.add(new JMenu("File"));
                fileMenu.add(mOpenAction);  // Note use of actions, not text.
                fileMenu.add(mSaveAction);
                fileMenu.addSeparator(); 
                fileMenu.add(mExitAction);
        return menuBar;
    }//end createMenuBar
    
    //============================================================ createActions
    /** Utility function to define actions. */
    private void createActions() {
        mOpenAction = new AbstractAction("Open...") {
            public void actionPerformed(ActionEvent e) {
                int retval = mFileChooser.showOpenDialog(NutPad.this);
                if (retval == JFileChooser.APPROVE_OPTION) {
                    File f = mFileChooser.getSelectedFile();
                    try {
                        FileReader reader = new FileReader(f);
                        mEditArea.read(reader, "");  // Use TextComponent read
                    } catch (IOException ioex) {
                        System.out.println(e);
                        System.exit(1);
                    }
                }
            }
        };
        
        mSaveAction = new AbstractAction("Save") {
            public void actionPerformed(ActionEvent e) {
                int retval = mFileChooser.showSaveDialog(NutPad.this);
                if (retval == JFileChooser.APPROVE_OPTION) {
                    File f = mFileChooser.getSelectedFile();
                    try {
                        FileWriter writer = new FileWriter(f);
                        mEditArea.write(writer);  // Use TextComponent write
                    } catch (IOException ioex) {
                        System.out.println(e);
                        System.exit(1);
                    }
                }
            }
        };
        
        mExitAction = new AbstractAction("Exit") {
            public void actionPerformed(ActionEvent e) {
                System.exit(0);
            }
        };
    }//end createActions    
}//end class NutPad
Copyleft 2004 Fred Swartz MIT License
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