🚀 go-pugleaf

Hello,

I am having a problem when throwing an exception with 
an associated String message, in that the message is not 
being displayed by the .getMessage() method in the 
associated catch block located in the calling procedure.

The exception is being propagated okay, but its message 
string is not.

I have appended the full code and output, but the main 
parts are:

Object pop() throws IndexOutOfBoundsException
{
  if(cnt<0)throw new IndexOutOfBoundsException("Queue underflow");
  return que[--cnt]; // testing IndexOutOfBoundsException message:
}

a call to which is caught in the caller catch block

catch(IndexOutOfBoundsException e)
{
  System.err.println(e.getMessage());  // reports null ???
  e.printStackTrace(System.err);
}

I have tried changing IndexOutOfBoundsException to just 
Exception, and to Throwable, with the same result.  I 
have also tried altering the code a bit so I could display 
the .getMessage() in the throwing method, and verified it 
displayed okay there, but it just disappears when the 
exception object is used in the caller.

Any suggestions or comments would be appreciated.

BJ

========= Code Listing of Thread3.java ==========
==== run with command line arguments a b c ======


public class Thread3
{
  public static void main(String[] args)
  {
    int argc = args.length;
    Queue q = new Queue(argc);

    try
    {
      for(int i=0;i<argc;i++)
      {
        q.push(args[i]);
      }

      for(int i=0;i<argc;i++)
      {
        System.out.println(" Main: " + (String)q.pop());
      }
    }
    catch(IndexOutOfBoundsException e)
    {
      // e.getMessage() contains "null" string here???
      System.err.println(e.getMessage());
      e.printStackTrace(System.err);
    }
  }
}

class Queue
{
  Object que[];
  int    max;
  int    cnt;

  public Queue(int max)
  {
    this.max = max;
    this.cnt = -1;
    this.que = new Object[max];
  }

  void push(Object o) throws IndexOutOfBoundsException
  {
    if(cnt>=max)throw new IndexOutOfBoundsException("Queue overflow");
    que[++cnt] = o;
  }

  Object pop() throws IndexOutOfBoundsException
  {
    if(cnt<0)throw new IndexOutOfBoundsException("Queue underflow");
    return que[--cnt]; // testing IndexOutOfBoundsException message:
  }
}

============== Output (JPadPro) ===============

---------------- JDK Debug Build ------------------
Compiling F:\Projects\JPadPro\Test\Thread\Thread3.java
Command line: "D:\Dev\Borland\JBuilder4\jdk1.3\bin\javac_g.exe"
     -deprecation -g -classpath "F:\Projects\JPadPro"
     "F:\Projects\JPadPro\Test\Thread\Thread3.java"
The current directory is: F:\Projects\JPadPro\Test\Thread
Finished

Starting application F:\Projects\JPadPro\Test\Thread\Thread3.class
Command line: "D:\Dev\Borland\JBuilder4\jdk1.3\bin\java_g.exe"
      -classpath "F:\Projects\JPadPro" Test.Thread.Thread3 a b c
The current directory is: F:\Projects\JPadPro\Test\Thread
 Main: b
 Main: a
null
java.lang.ArrayIndexOutOfBoundsException
	at Test.Thread.Queue.pop(Thread3.java:62)
	at Test.Thread.Thread3.main(Thread3.java:25)
Interactive Session Ended