need stack help

**ali1** · 11-05-2011, 08:29 PM

First i create simple claculator.but now I am trying to change it to RPN calculator by using stack.Can some one help me((especially where to use pop method) because I don't know alot about stack.here is my codes so far.

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

import javax.swing.event.*;
import java.util.Stack;

public class CalcGUIPanel extends JPanel
{

Stack s=new Stack();

//--\- Component referenced during execution

private JTextField displayField; // display result / input.

//--\- Variables representing state of the calculator

private boolean startNumber = true; // true: num key next

private int resultValue = 0; // result so far

private String previousOp = "="; // previous operation

//========================================= static (class) variables

private static final Font BIGGER_FONT =

new Font("monspaced", Font.PLAIN, 20);

//================================================== ==== constructor

public CalcGUIPanel()
{

//--\- Display field

displayField = new JTextField();

//--\- Clear button

JButton clearButton = new JButton("CLEAR");

clearButton.setFont(BIGGER_FONT);

clearButton.addActionListener(new ClearListener());

//--\- One listener for all numeric keys.

ActionListener numListener = new NumListener();

//--\- Layout numeric keys in a grid. Generate the buttons

// in a loop from the chars in a string.

String buttonOrder = "789456123 0 ";

JPanel buttonPanel = new JPanel(new GridLayout(5, 3));

for (int i = 0; i < buttonOrder.length(); i++) {

String keyTop = buttonOrder.substring(i, i+1);

if (keyTop.equals(" ")) {

buttonPanel.add(new JLabel(""));

} else {

JButton b = new JButton(keyTop);

b.addActionListener(numListener);
s.push("0");
s.push("1");
s.push("2");
s.push("3");
s.push("4");
s.push("5");
s.push("6");
s.push("7");
s.push("8");
s.push("9");

b.setFont(BIGGER_FONT);

buttonPanel.add(B);

}

}

//--\- One ActionListener to use for all operator buttons.

ActionListener opListener = new OpListener();

//--\- Create panel with gridlayout to hold operator buttons.

// Use array of button names to create buttons in a loop.

JPanel opPanel = new JPanel(new GridLayout(5, 1));

String[] opOrder = {"+", "-", "*", "/", "enter"};

for (int i = 0; i < opOrder.length; i++) {

JButton b = new JButton(opOrder[i]);

b.addActionListener(opListener);

s.push("+");
s.push("-");
s.push("*");
s.push("/");
s.push("enter");

b.setFont(BIGGER_FONT);

opPanel.add(B);

}

//--\- Layout the top-level panel.

this.setLayout(new BorderLayout());

this.add(displayField, BorderLayout.NORTH );

this.add(buttonPanel , BorderLayout.CENTER);

this.add(opPanel , BorderLayout.EAST );

this.add(clearButton , BorderLayout.SOUTH );

}//end constructor

//================================================== ==== action_clear

/*\* Called by Clear btn action listener and elsewhere.*/

private void action_clear() {

startNumber = true;

displayField.setText("0");

resultValue = 0;

previousOp = "=";

}

// inner listener class OpListener

/*\* Listener for all op buttons. \*/

class OpListener implements ActionListener {

public void actionPerformed(ActionEvent e) {

// The calculator is always in one of two states.

// 1. A number must be entered \-\- this operator is wrong.

// 2. An operator must be entered \-\- we're ok.

{

startNumber = true; // Next thing must be a number

try {

// Get value from display field, convert, do prev op

// If this is the first op, \_previousOp will be =.

String displayText = displayField.getText();

int currentValue = Integer.parseInt(displayText);

if (previousOp.equals("=")) {

resultValue = currentValue;

} else if (previousOp.equals("+")) {

resultValue += currentValue;

} else if (previousOp.equals("-")) {

resultValue -= currentValue;

} else if (previousOp.equals("*")) {

resultValue *= currentValue;

} else if (previousOp.equals("/")) {

resultValue /= currentValue;

}

displayField.setText(""+resultValue);

} catch (NumberFormatException ex) {

action_clear();

displayField.setText("Error");

}

//--\- set \_previousOp for the next operator.

previousOp = e.getActionCommand();

}//endif \_startNumber

}//endmethod

}//end class

//////////////////////////////////// inner listener class ClearListener

// Action listener for numeric keys

class NumListener implements ActionListener {

public void actionPerformed(ActionEvent e) {

String digit = e.getActionCommand(); // Get text from button

if (startNumber) {

// This is the first digit, clear field and set

displayField.setText(digit);

startNumber = false;

} else {

// Add this digit to the end of the display field

displayField.setText(displayField.getText() + digit);

}

}

}//end class

//inner listener class ClearListener

class ClearListener implements ActionListener {

public void actionPerformed(ActionEvent e) {

action_clear();

}

}

}

**Fubarable** · 11-05-2011, 08:34 PM

It is very hard to read your code since you're using [quote] [/quote] tags and not [code] [/code] around your code. Could you please edit your question to use the code tags?

**ali1** · 11-05-2011, 08:37 PM

First i create simple claculator.but now I am trying to change it to RPN calculator by using stack.Can some one help me((especially where to use pop method) because I don't know alot about stack.here is my codes so far.

import java.awt.event.*;

import javax.swing.*;

import javax.swing.event.*;
import java.util.Scanner;

public class CalcGUIPanel extends JPanel
{

Stack s=new Stack();

//--\- Component referenced during execution

private JTextField displayField; // display result / input.

//--\- Variables representing state of the calculator

private boolean startNumber = true; // true: num key next

private int resultValue = 0; // result so far

private String previousOp = "="; // previous operation

//========================================= static (class) variables

private static final Font BIGGER_FONT =

new Font("monspaced", Font.PLAIN, 20);

//================================================== ==== constructor

public CalcGUIPanel()
{

//--\- Display field

displayField = new JTextField();

//--\- Clear button

JButton clearButton = new JButton("CLEAR");

clearButton.setFont(BIGGER_FONT);

clearButton.addActionListener(new ClearListener());

//--\- One listener for all numeric keys.

ActionListener numListener = new NumListener();

//--\- Layout numeric keys in a grid. Generate the buttons

// in a loop from the chars in a string.

String buttonOrder = "789456123 0 ";

JPanel buttonPanel = new JPanel(new GridLayout(5, 3));

for (int i = 0; i < buttonOrder.length(); i++) {

String keyTop = buttonOrder.substring(i, i+1);

if (keyTop.equals(" ")) {

buttonPanel.add(new JLabel(""));

} else {

JButton b = new JButton(keyTop);

b.addActionListener(numListener);
s.push("0");
s.push("1");
s.push("2");
s.push("3");
s.push("4");
s.push("5");
s.push("6");
s.push("7");
s.push("8");
s.push("9");

b.setFont(BIGGER_FONT);

buttonPanel.add(B);

}

}

//--\- One ActionListener to use for all operator buttons.

ActionListener opListener = new OpListener();

//--\- Create panel with gridlayout to hold operator buttons.

// Use array of button names to create buttons in a loop.

JPanel opPanel = new JPanel(new GridLayout(5, 1));

String[] opOrder = {"+", "-", "*", "/", "enter"};

for (int i = 0; i < opOrder.length; i++) {

JButton b = new JButton(opOrder[i]);

b.addActionListener(opListener);

s.push("+");
s.push("-");
s.push("*");
s.push("/");
s.push("enter");

b.setFont(BIGGER_FONT);

opPanel.add(B);

}

//--\- Layout the top-level panel.

this.setLayout(new BorderLayout());

this.add(displayField, BorderLayout.NORTH );

this.add(buttonPanel , BorderLayout.CENTER);

this.add(opPanel , BorderLayout.EAST );

this.add(clearButton , BorderLayout.SOUTH );

}//end constructor

//================================================== ==== action_clear

/*\* Called by Clear btn action listener and elsewhere.*/

private void action_clear() {

startNumber = true;

displayField.setText("0");

resultValue = 0;

previousOp = "=";

}

// inner listener class OpListener

/*\* Listener for all op buttons. \*/

class OpListener implements ActionListener {

public void actionPerformed(ActionEvent e) {

// The calculator is always in one of two states.

// 1. A number must be entered \-\- this operator is wrong.

// 2. An operator must be entered \-\- we're ok.

{

startNumber = true; // Next thing must be a number

try {

// Get value from display field, convert, do prev op

// If this is the first op, \_previousOp will be =.

String displayText = displayField.getText();

int currentValue = Integer.parseInt(displayText);

if (previousOp.equals("=")) {

resultValue = currentValue;

} else if (previousOp.equals("+")) {

resultValue += currentValue;

} else if (previousOp.equals("-")) {

resultValue -= currentValue;

} else if (previousOp.equals("*")) {

resultValue *= currentValue;

} else if (previousOp.equals("/")) {

resultValue /= currentValue;

}

displayField.setText(""+resultValue);

} catch (NumberFormatException ex) {

action_clear();

displayField.setText("Error");

}

//--\- set \_previousOp for the next operator.

previousOp = e.getActionCommand();

}//endif \_startNumber

}//endmethod

}//end class

//////////////////////////////////// inner listener class ClearListener

// Action listener for numeric keys

class NumListener implements ActionListener {

public void actionPerformed(ActionEvent e) {

String digit = e.getActionCommand(); // Get text from button

if (startNumber) {

// This is the first digit, clear field and set

displayField.setText(digit);

startNumber = false;

} else {

// Add this digit to the end of the display field

displayField.setText(displayField.getText() + digit);

}

}

}//end class

//inner listener class ClearListener

class ClearListener implements ActionListener {

public void actionPerformed(ActionEvent e) {

action_clear();

}

}

}

**Fubarable** · 11-05-2011, 08:38 PM

Again your posted code is near impossible to read, again you'll want to use the tag [code] on top of your code block and the tag [/code] below your code block. For example which is easier to read, your posts or this?:

Java Code:

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

public class CalcGuiPanel extends JPanel {
   Stack s = new Stack();
   // --\- Component referenced during execution
   private JTextField displayField; // display result / input.
   // --\- Variables representing state of the calculator
   private boolean startNumber = true; // true: num key next
   private int resultValue = 0; // result so far
   private String previousOp = "="; // previous operation
   // ========================================= static (class) variables
   private static final Font BIGGER_FONT = new Font("monspaced", Font.PLAIN, 20);

   // ====================================================== constructor
   public CalcGuiPanel() {
      // --\- Display field
      displayField = new JTextField();
      // --\- Clear button
      JButton clearButton = new JButton("CLEAR");
      clearButton.setFont(BIGGER_FONT);
      clearButton.addActionListener(new ClearListener());
      // --\- One listener for all numeric keys.
      ActionListener numListener = new NumListener();
      // --\- Layout numeric keys in a grid. Generate the buttons
      // in a loop from the chars in a string.
      String buttonOrder = "789456123 0 ";
      JPanel buttonPanel = new JPanel(new GridLayout(5, 3));
      for (int i = 0; i < buttonOrder.length(); i++) {
         String keyTop = buttonOrder.substring(i, i + 1);
         if (keyTop.equals(" ")) {
            buttonPanel.add(new JLabel(""));
         } else {
            JButton b = new JButton(keyTop);
            b.addActionListener(numListener);
            s.push("0");
            s.push("1");
            s.push("2");
            s.push("3");
            s.push("4");
            s.push("5");
            s.push("6");
            s.push("7");
            s.push("8");
            s.push("9");
            b.setFont(BIGGER_FONT);
            buttonPanel.add(b); //!! change B to b
         }
      }
      // --\- One ActionListener to use for all operator buttons.
      ActionListener opListener = new OpListener();
      // --\- Create panel with gridlayout to hold operator buttons.
      // Use array of button names to create buttons in a loop.
      JPanel opPanel = new JPanel(new GridLayout(5, 1));
      String[] opOrder = { "+", "-", "*", "/", "enter" };
      for (int i = 0; i < opOrder.length; i++) {
         JButton b = new JButton(opOrder[i]);
         b.addActionListener(opListener);
         s.push("+");
         s.push("-");
         s.push("*");
         s.push("/");
         s.push("enter");
         b.setFont(BIGGER_FONT);
         opPanel.add(b); //!! change B to b
      }
      // --\- Layout the top-level panel.
      this.setLayout(new BorderLayout());
      this.add(displayField, BorderLayout.NORTH);
      this.add(buttonPanel, BorderLayout.CENTER);
      this.add(opPanel, BorderLayout.EAST);
      this.add(clearButton, BorderLayout.SOUTH);
   }// end constructor
    // ====================================================== action_clear

   /* \* Called by Clear btn action listener and elsewhere. */
   private void action_clear() {
      startNumber = true;
      displayField.setText("0");
      resultValue = 0;
      previousOp = "=";
   }

   // inner listener class OpListener
   /* \* Listener for all op buttons. \ */
   class OpListener implements ActionListener {
      public void actionPerformed(ActionEvent e) {
         // The calculator is always in one of two states.
         // 1. A number must be entered \-\- this operator is wrong.
         // 2. An operator must be entered \-\- we're ok.
         {
            startNumber = true; // Next thing must be a number
            try {
               // Get value from display field, convert, do prev op
               // If this is the first op, \_previousOp will be =.
               String displayText = displayField.getText();
               int currentValue = Integer.parseInt(displayText);
               if (previousOp.equals("=")) {
                  resultValue = currentValue;
               } else if (previousOp.equals("+")) {
                  resultValue += currentValue;
               } else if (previousOp.equals("-")) {
                  resultValue -= currentValue;
               } else if (previousOp.equals("*")) {
                  resultValue *= currentValue;
               } else if (previousOp.equals("/")) {
                  resultValue /= currentValue;
               }
               displayField.setText("" + resultValue);
            } catch (NumberFormatException ex) {
               action_clear();
               displayField.setText("Error");
            }
            // --\- set \_previousOp for the next operator.
            previousOp = e.getActionCommand();
         }// endif \_startNumber
      }// endmethod
   }// end class
    // ////////////////////////////////// inner listener class ClearListener
    // Action listener for numeric keys

   class NumListener implements ActionListener {
      public void actionPerformed(ActionEvent e) {
         String digit = e.getActionCommand(); // Get text from button
         if (startNumber) {
            // This is the first digit, clear field and set
            displayField.setText(digit);
            startNumber = false;
         } else {
            // Add this digit to the end of the display field
            displayField.setText(displayField.getText() + digit);
         }
      }
   }// end class
    // inner listener class ClearListener

   class ClearListener implements ActionListener {
      public void actionPerformed(ActionEvent e) {
         action_clear();
      }
   }
}

**Fubarable** · 11-05-2011, 08:48 PM

Next, I suggest that you work out your stack logic in a separate simpler non-GUI class. After you've gotten the bugs out in this simpler environment, only then add the code to your main program.