macOS javac and java commands from Terminal

[toddburch]

Ok, starting to code a bit here on the mac. OS X 10.4.8 on a new Intel MacPro. Java -version is:

java version "1.5.0_06"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0_06-113)
Java HotSpot(TM) Client VM (build 1.5.0_06-68, mixed mode, sharing)


After I write my code (using Textwrangler) I open Terminal, and type:

javac /Users/toddburch/Documents/myjava/MyClass.java

and it works fine. Then, I type

java MyClass /Users/toddburch/Documents/myjava

and I get the "Hello World" written to stdout. So far, so good.

With my longer test program that throws up a couple dialog boxes, I do the same things:

javac /Users/toddburch/Documents/myjava/MessageDialogDemo.java

and it works fine too, other than giving me a warning for a deprecacted function. This time, though, I get additional .class files. Instead of just getting:

MessageDialog.class and
MessageDialogDemo.class, I also get
MessageDialog$1.class and
MessageDialogDemo$1.class. What's up with these?

Then, again from the root directory (/), as before, I enter

java MessageDialogDemo /Users/toddburch/Documents/myjava

and I ALWAYS get:

Exception in thread "main" java.lang.NoClassDefFoundError: MessageDialogDemo

If I "cd Documents/myjava" and enter

java MessageDialogDemo

It works fine! I'm pulling my hair out here. Why is an exception occuring when I provide the path from the command line with this second program and not the first? Could it be a classpath issue, where MessageDialog.class is not being found? If so, how to fix?

...
hmmmmm... thinking... trying another test
....

OK, I tried the -verbose option, and that didn't shed any light on this. I then tried providing a classpath:

java -cp</Users/toddburch/Documents/myjava> MessageDialogDemo /Users/toddburch/Documents/myjava

This time, bash returned, with no error message, and no program output. What could this be? Are there considerations with running a GUI from within a shell command line?

I can post the code if that would be helpful - it's an example from a Java book I typed up.

Sorry for the long post - but that's where I'm at. Todd

 

[robbieduncan]

The $ .class files normally get generated if you are using inner classes (do you define a class inside another class definition).

The other problem sounds like a CLASSPATH issue.

 

[toddburch]

I guess I do. Here's the code:

import java.awt.* ; 
import java.awt.event.* ; 

public class MessageDialogDemo extends Frame
implements ActionListener 
{ 
  Button b ; 
  
  public static void main(String args[])
  { 
    MessageDialogDemo mdd = new MessageDialogDemo() ; 
    mdd.setVisible(true) ; 
    mdd.setSize(200,100) ; 
  } 
  
  MessageDialogDemo()
  { 
    super("Message Dialog Demo"); 
    
    // set layout manager 
    setLayout(new FlowLayout()) ; 
    
    //Create a button 
    b = new Button("Message Dialog") ; 
    b.addActionListener(this) ; 
    add(b) ; 
    
    // Anonymous inner class handles window events 
    addWindowListener(new WindowAdapter()
    { 
      public void windowClosing(WindowEvent we)
      { 
        System.exit(0) ; 
      }
    }) ; 
  } 

  public void actionPerformed(ActionEvent ae)
  { 
    String message = "This is a message." ; 
    MessageDialog md = new MessageDialog(this, "Message Dialog", true, message);
    md.show() ; 
   }
 }
 
 class MessageDialog extends Dialog
 implements ActionListener
 {
 Button ok ; 
 
 MessageDialog(Frame parent, String title, boolean mode, String message)
   { 
   super(parent, title, mode) ; 
   
   //create and add "Center" panel 
   Panel pc = new Panel() ; 
   Label label = new Label(message) ; 
   pc.add(label) ; 
   add(pc,"Center") ; 
   
   // create and add a "South" panel 
   Panel ps = new Panel() ; 
   ok = new Button("OK") ; 
   ok.addActionListener(this) ; 
   ps.add(ok) ; 
   add(ps,"South") ; 
   
   //Lay out components and set the intial size of this dialog box 
   pack() ; 
   
   //Anonymous inner class handles window events 
   addWindowListener(new WindowAdapter()  
     { 
     public void windowClosing(WindowEvent we)
       { 
         System.exit(0) ; 
       } 
      }) ; 
   } 
 
   public Insets getInsets() 
     { 
       return new Insets(40,20,20,20) ; 
     } 
 
 public void actionPerformed(ActionEvent ae)
   {  
     dispose() ; 
   } 
 }

 

[toddburch]

OK, I figured it out. It was a syntax issue with the -cp spec. This works:

java -cp /Users/toddburch/Documents/myjava MessageDialogDemo /Users/toddburch/Documents/myjava

I had used the < and > before - not needed.

Thanks!

EDIT: This works too, and is shorter:

java -cp /Users/toddburch/Documents/myjava MessageDialogDemo