pbl, on 23 October 2012 - 10:59 AM, said:

the first integer in the series is the time you start the job.
the second integer in the series is the time you finish the job.
the third is the amount of money you are paid for the job. You are misunderstanding what the numbers in the series mean.

here is my current code..at runtime I receive java.lang.NullPointerException at lines 54 & 42

public class StacksGUI extends JFrame implements ActionListener{
  JLabel inputLabel, outputLabel;
  JButton enterButton, clearButton;
  JTextField inputText, outputText;
  String strInput;
  Stack intStack;
  int strToken;
  char digit;
  StringBuilder sb;
  
  public StacksGUI(){
    setLayout(new FlowLayout());
    
    inputLabel = new JLabel("Positive Integers: ");
    add(inputLabel);
    
    inputText = new JTextField(15);
    add(inputText);
    
    outputLabel = new JLabel(" Integers in reverse: ");
    add(outputLabel);
    
    outputText = new JTextField(15);
    add(outputText);
    
    enterButton = new JButton("Enter");
    add(enterButton);
    
    clearButton = new JButton("Clear Textfields");
    add(clearButton);
    
    inputText.addActionListener(this);
    outputText.addActionListener(this);
    enterButton.addActionListener(this);
    clearButton.addActionListener(this);
  }
    public void actionPerformed(ActionEvent ae) {

    strInput = inputText.getText();
    
    if (ae.getSource().equals(enterButton))
      reverse(strInput);
    if (ae.getSource().equals(clearButton))
      clearText();
    
    }
    void clearText(){
      inputText.setText("");
      outputText.setText("");
    }
    void reverse(String strInput){
      for(int i = 0; i < strInput.length(); i++){
        digit = strInput.charAt(i);
        intStack.push(digit - '0');
      }
      while(!intStack.isEmpty()){
      sb.append(intStack.pop());
      }
      outputText.setText(sb.toString());
      
    }
    public static void main(String[] args) {
    StacksGUI stack = new StacksGUI();
    stack.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    stack.setLocationByPlatform(true);
    stack.setSize(220, 400);
    stack.setVisible(true);
  }
}

Thank you! do you have any suggestion for printing the stack to the JTextField

Thank you for your suggestions. They were very helpful but the strInput is a string of integers so I do not want to use the char digit = strInput.charAt(i). I need an alternative for that in terms of integers

CasiOo, I do not understand your suggestion. I realize you are challenging me to come up with a solution but I do not believe I am able to do so. Thanks to all of you for the help thus far