CharStack class works with javac but does not return anything in Eclipse console

Question

I'm trying to modify the CharStack class (below) in Eclipse, but I'm unable to get it to do anything in the console when I run it, though it works fine when compiled with javac.exe

Is this something to do with carriage returns, perhaps? How do I signal to Eclipse that I'm ready for it to accept the input and return a result (the -1)?

The algorithm for the class is just:

while (there is a character to read)     
    push the character onto a stack;

while (there are characters on the stack)     
    pop off a character and print it;

The concept of a stack is a perfect candidate for becoming a class. It has a well-defined interface (push() and pop()) and some rules to enforce (you can only take data from the top, you can only remove as many elements as you insert). Here is a simple implementation of a stack that holds characters:

import java.io.*;
public class CharStack
{
  private char[] m_data;          

  private int m_ptr;

  public CharStack(int size)
  {
      m_ptr = 0;                  

      m_data = new char[(size > 1 ? size : 10)]; 
  }

  public void push(char c)
  {
      if (m_ptr >= m_data.length) 
      {
         // Grow the array automatically
         char[] tmp = 
            new char[m_data.length * 2];

         System.arraycopy(m_data, 0, 
                          tmp, 0, 
                          m_data.length);
         m_data = tmp;
      }
      m_data[m_ptr++] = c;
  }

  public char pop()              
  {
      return m_data[--m_ptr];
  }
  public boolean hasMoreElements()
  {
      return (m_ptr != 0);
  }


  public static void main(String[] argv) 
      throws IOException
  {
      CharStack s = new CharStack(10);
      int i;
      while ( (i = System.in.read()) != -1 )
      {
         s.push((char) i);
      }
      while (s.hasMoreElements())
      {
         System.out.write(s.pop());
      }
      System.out.println();
    }
}

When I run this in Windows CLI I get:

C:\user>java CharStack
12345

54321

_I'm unable to get it to do anything in the console when I run it_ What did you want it to do? What did you expect to happen? Why did you expect that? What does it actually do? — Sotirios Delimanolis, Oct 19 '15 at 16:10
@Iyen I don't know; this is written by a prof at Berkeley, not me. Ctrl+C doesn't work in the Eclipse console. Pressing enter works with the Windows CLI. — , Oct 19 '15 at 16:41
@SotiriosDelimanolis I expect it to return something. It doesn't return anything. The specifics are kind of irrelevant, but I'll update the post. — , Oct 19 '15 at 16:42

score 1 · Accepted Answer · answered Oct 19 '15 at 16:50

1

What you're looking for is the EOF character, represented OS-agnostically in this Java class.

In Windows that would be Ctrl-Z. Presumably this is implicit when you're on the Windows CLI version, but not so in Eclipse.

answered Oct 19 '15 at 16:50

`CTRL-D` under linux, see also http://stackoverflow.com/questions/3061135/can-we-write-an-eof-character-ourselves – Oct 19 '15 at 16:56

CharStack class works with javac but does not return anything in Eclipse console

1 Answers1