Help with swing
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Thread: Help with swing

  1. #1
    Join Date
    Feb 2008
    Posts
    24

    Help with swing

    Hey ive only been programming java for about a month now and im a little stuck:/

    Basically im making a basic text editor in java, at the moment im trying to load text from a file to a text area but i get this compile error

    Code:
    TextEditor.java:123: cannot find symbol
    symbol  : variable edit
    location: class TextEditor
    					edit.setText(line);
    					^
    Anyone have any idea what im doing wrong?
    Heres my code:
    Code:
    import java.awt.*;
    import java.awt.event.*;
    import javax.swing.*;
    import java.io.*;
    
    public class TextEditor extends JFrame implements ActionListener {
    	//create icons used in toolbar
    	ImageIcon loadIcon = new ImageIcon("load.gif");
    	ImageIcon saveIcon = new ImageIcon("save.gif");
    	ImageIcon spellIcon = new ImageIcon("spelling.gif");
    	ImageIcon undoIcon = new ImageIcon("back.gif");
    	ImageIcon newIcon = new ImageIcon("subscribe.gif");
    	//create buttons
    	JButton load = new JButton("Load", loadIcon);
    	JButton save = new JButton("Save", saveIcon);
    	JButton spell = new JButton("Spell Check", spellIcon);
    	JButton undo = new JButton("Undo", undoIcon);
    	JButton p_new = new JButton("New", newIcon);
    	//constructor
    	public TextEditor() {
    		super("Text Editor");
    		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    		//add buttons to the toolbar
    		JToolBar bar = new JToolBar();
    		bar.add(p_new);
    		bar.add(load);
    		bar.add(save);
    		bar.add(spell);
    		bar.add(undo);
    		//create menu
    		//menu items
    		JMenuItem menuLoad = new JMenuItem("Load");
    		JMenuItem menuSave = new JMenuItem("Save");
    		JMenuItem menuSpell = new JMenuItem("Spell Check");
    		JMenuItem menuUndo = new JMenuItem("Undo");
    		JMenuItem menuNew = new JMenuItem("New");
    		JMenuItem menuPrint = new JMenuItem("Print");
    		JMenuItem menuAbout = new JMenuItem("About");
    		JMenuItem menuToolbar = new JMenuItem("Toolbar");
    		JMenuItem menuStatusbar = new JMenuItem("Statusbar");
    		//5 menus
    		JMenuBar menubar = new JMenuBar();
    		JMenu menu = new JMenu("File");
    		JMenu menu2 = new JMenu("Edit");
    		JMenu menu3 = new JMenu("Tools");
    		JMenu menu4 = new JMenu("View");
    		JMenu menu5 = new JMenu("Help");
    		//add items to menu
    		menu.add(menuNew);
    		menu.addSeparator();
    		menu.add(menuLoad);
    		menu.add(menuSave);
    		menu.addSeparator();
    		menu.add(menuPrint);
    		menu3.add(menuSpell);
    		menu2.add(menuUndo);
    		menu5.add(menuAbout);
    		menu4.add(menuToolbar);
    		menu4.add(menuStatusbar);
    		menubar.add(menu);
    		menubar.add(menu2);
    		menubar.add(menu3);
    		menubar.add(menu4);
    		menubar.add(menu5);	
    		//listen for button clicks
    		load.addActionListener(this);
    		save.addActionListener(this);
    		p_new.addActionListener(this);
    		spell.addActionListener(this);
    		undo.addActionListener(this);
    		//prepare user interface
    		JTextArea edit = new JTextArea(40, 120);
    		JScrollPane scroll = new JScrollPane(edit);
    		BorderLayout bord = new BorderLayout();
    		setLayout(bord);
    		add("North", bar);
    		add("Center", scroll);
    		setJMenuBar(menubar);
    		setSize(800, 600);
    		pack();
    		setVisible(true);
    	}
    
    	//button clicks
    	public void actionPerformed(ActionEvent evt) {
    		Object source = evt.getSource();
    		if (source == load) {
    			loadFile();
    		}
    		if (source == save) {
    			saveFile();
    		}
    		if (source == p_new) {
    			setTitle("New!");
    			repaint();
    		}
    		if (source == spell) {
    			setTitle("Spell!");
    			repaint();
    		}
    		if (source == undo) {
    			setTitle("Undo!");
    			repaint();
    		}
    
    	}
    	//Loads text into text editor
    	void loadFile()
    	{
    		try {
    
    			FileReader file = new
    
    				FileReader("myfile.txt");
    
    			BufferedReader buff = new
    
    				BufferedReader(file);
    
    			boolean eof = false;
    
    			while (!eof) {
    
    				String line = buff.readLine();
    
    				if (line == null)
    
    					eof = true;
    
    				else
    
    					edit.setText(line);
    
    				}
    
    				buff.close();
    
    			} catch (IOException e) {
    
    				System.out.println("Error -- " + e.toString());
    
    			}
    	}
    	//saves text into file
    	void saveFile()
    	{
    		FileOutputStream fout;		
    		try
    		{
    			fout = new FileOutputStream ("myfile.txt");
    			new PrintStream(fout).println ("hello world!");
    			fout.close();		
    		}
    		catch (IOException e)
    		{
    			System.err.println ("Unable to write to file");
    			System.exit(-1);
    		}
    	}
    
    	//main function
    	public static void main(String[] arguments) {
    		TextEditor main = new TextEditor();
    	}
    }
    Thanks for any help!

  2. #2
    dlorde is offline Elite Member Power Poster
    Join Date
    Aug 1999
    Location
    UK
    Posts
    10,163

    Re: Help with swing

    You're declaring JTextArea edit as a local variable in the constructor. As soon as the constructor finishes, it goes out of scope. You need to declare it as a class field and initialize it in the constructor. Then it will be visible and available to all instance methods.

    I have always wished that my computer would be as easy to use as my telephone. My wish has come true. I no longer know how to use my telephone...
    Bjarne Stroustrup
    Please use [CODE]...your code here...[/CODE] tags when posting code. If you get an error, please post the full error message and stack trace, if present.

  3. #3
    Join Date
    Feb 2008
    Posts
    24

    Re: Help with swing

    Thanks alot for your help!
    Completely forgot about moving that one!

  4. #4
    Join Date
    Feb 2008
    Posts
    24

    Re: Help with swing

    Sorry another quick question, how do i add text to the text area without deleting the rest, eg at the moment im using:
    Code:
    				edit.setText(line);
    Which just puts the last line of text on the screen.

  5. #5
    Join Date
    Apr 2007
    Posts
    442

    Re: Help with swing

    like,

    edit.setText(edit.getText()+text);

  6. #6
    Join Date
    May 2006
    Location
    UK
    Posts
    4,474

    Re: Help with swing

    Always read the API docs they list all the available methods such as append(text) which could be just what you are after.

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