Menus Not Displaying

[kahaj]

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



public class NotepadInJava //implements ActionListener
{
    //preparing container
    JFrame notepadFrame;
    JTextArea theTextArea;
    JScrollPane scrollPane = new JScrollPane(theTextArea);


    //File menu items
    JMenu file;
    JMenuItem open;
    JMenuItem save;
    JMenuItem exit;

    //Edit menu items
    JMenu edit;
    JMenuItem copy;
    JMenuItem cut;
    JMenuItem selectAll;
    JMenuItem paste;

    public static void main(String[] args)
    {
        NotepadInJava app = new NotepadInJava();
    }

    public NotepadInJava()
    {
        notepadFrame = new JFrame();
        notepadFrame.addWindowListener(null);
        notepadFrame.setSize(600,600);
        notepadFrame.setLocation(40,20);
        notepadFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        notepadFrame.setVisible(true);
        buildMenus();
    }

    private void buildMenus()
    {
      //create menu bar
        JMenuBar MenuBar = new JMenuBar();
      //notepadFrame.setJMenuBar(FileMenuBar);

      //build File menu
        file = new JMenu("File");
        MenuBar.add(file);
      //add Open to File menu
        open = new JMenuItem("Open");
        open.addActionListener(null);
        MenuBar.add(open);
      //add Save to File category
        save = new JMenuItem("Save");
        save.addActionListener(null);
        MenuBar.add(save);
      //add Exit to File category
        exit = new JMenuItem("Exit");
        exit.addActionListener(null);
        MenuBar.add(exit);

      //build Edit menu
        edit = new JMenu("Edit");
        MenuBar.add(edit);
      //add Copy to Edit category
        copy = new JMenuItem("Copy");
        copy.addActionListener(null);
        MenuBar.add(copy);
      //add Cut to Edit category
        cut = new JMenuItem("Cut");
        cut.addActionListener(null);
        MenuBar.add(cut);
      //add Select All to Edit category
        selectAll = new JMenuItem("Select All");
        selectAll.addActionListener(null);
        MenuBar.add(selectAll);
      //add Paste to Edit category
        paste = new JMenuItem("Paste");
        paste.addActionListener(null);
        MenuBar.add(paste);
    }
}

[r035198x]

Please use code tags if you have to post code.
You never set the Menubar to the frame

notepadFrame.setJMenuBar(MenuBar);

That means you will need to make your MuneBar be visible in the method where you create the frame. Also only setVisible(true) after you have finished dressing the frame.

[kahaj]

Sorry, I hit Enter before putting the code tags or even posting my problem.

I'm trying to learn Java from the Sun website. The menus aren't showing on this simple app.

Inside of

private void buildMenus()

I commented out

//notepadFrame.setJMenuBar(FileMenuBar);

after realizing I had done several things incorrectly.

I just changed this line to

notepadFrame.setJMenuBar(MenuBar);

inside of

private void buildMenus()

Unfortunately, the menus are still not showing up.

[mcashe]

I'm not certain about this but in your constructor, you're actually displaying the frame before you call the buildMenus method. Try calling this method before your setVisible(true) statement.

[kahaj]

Here's the code I have so far:

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



public class NotepadInJava //implements ActionListener
{
    //preparing container
    JFrame notepadFrame;
    JMenuBar MenuBar;
    JTextArea theTextArea;
    JScrollPane scrollPane = new JScrollPane(theTextArea);


    //File menu items
    JMenu file;
    JMenuItem open;
    JMenuItem save;
    JMenuItem exit;

    //Edit menu items
    JMenu edit;
    JMenuItem copy;
    JMenuItem cut;
    JMenuItem selectAll;
    JMenuItem paste;

    public static void main(String[] args)
    {
        NotepadInJava app = new NotepadInJava();
    }

    public NotepadInJava()
    {
        buildMenus();
        notepadFrame = new JFrame();
        notepadFrame.add(MenuBar);
        notepadFrame.addWindowListener(null);
        notepadFrame.setSize(600,600);
        notepadFrame.setLocation(40,20);
        notepadFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        notepadFrame.setVisible(true);      
    }

    private void buildMenus()
    {
      //create menu bar
        JMenuBar MenuBar = new JMenuBar();
        notepadFrame.setJMenuBar(MenuBar);

      //build File menu
        file = new JMenu("File");
        MenuBar.add(file);
      //add Open to File menu
        open = new JMenuItem("Open");
        open.addActionListener(null);
        MenuBar.add(open);
      //add Save to File category
        save = new JMenuItem("Save");
        save.addActionListener(null);
        MenuBar.add(save);
      //add Exit to File category
        exit = new JMenuItem("Exit");
        exit.addActionListener(null);
        MenuBar.add(exit);

      //build Edit menu
        edit = new JMenu("Edit");
        MenuBar.add(edit);
      //add Copy to Edit category
        copy = new JMenuItem("Copy");
        copy.addActionListener(null);
        MenuBar.add(copy);
      //add Cut to Edit category
        cut = new JMenuItem("Cut");
        cut.addActionListener(null);
        MenuBar.add(cut);
      //add Select All to Edit category
        selectAll = new JMenuItem("Select All");
        selectAll.addActionListener(null);
        MenuBar.add(selectAll);
      //add Paste to Edit category
        paste = new JMenuItem("Paste");
        paste.addActionListener(null);
        MenuBar.add(paste);
    }
}

...and here's what the Debugger is yelling at me. To be totally honest, I'm not grasping what it is not liking about it.

run:
Exception in thread "main" java.lang.NullPointerException
        at NotepadInJava.buildMenus(NotepadInJava.java:50)
        at NotepadInJava.<init>(NotepadInJava.java:36)
        at NotepadInJava.main(NotepadInJava.java:31)
Java Result: 1
BUILD SUCCESSFUL (total time: 2 seconds)

[Fubarable]

Sorry, I hit Enter before putting the code tags or even posting my problem.

You can still edit your previous posts. I have taken the liberty of adding code tags.

...Unfortunately, the menus are still not showing up.

Let's see your most recent attempt at this project, but please use code tags. Thanks

[Fubarable]

Now you're calling buildMenus before you have initialized the JFrame. When you try to add the menus to the currently null JFrame, you are causing a NPE. Solution, create the JFrame first.

[Fubarable]

Also, you've got two JMenuBar objects you know. You'll likely want to have only one.

[kahaj]

Sorry, but I'm brand new to Java. Trying to take a stab and see what I can do with it...

I thought that I created the JFrame right off at class level with:

JFrame notepadFrame;

Also, what is an "NPE"?

[Fubarable]

NPE means Null Pointer Exception or NullPointerException. It happens when you try to call a method on an variable that does not reference an object.

[Fubarable]

[QUOTE=kahaj;83415]I thought that I created the JFrame right off at class level with:

JFrame notepadFrame;

This code creates a JFrame variable, but the variable doesn't refer to an object just yet but rather has nothing or null. To initialize a JFrame object you should call new JFrame(), for instance:

JFrame notepadFrame = new JFrame("My JFrame");

[kahaj]

Okay, I have it all figured out now. It works fine. Thanks so much for everyone's help w/ this.

[Fubarable]

Congrats! Good luck with your coding.