Please Help/ GUI Calculator

Question

I'm trying to create a GUI Calculator but cannot get my program to compile. Please could someone assistm, thanks.
import java.io.*;
import java.util.*;
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class CalculatorFrame extends JFrame
     private Container contentPane;
     //The componenets used in the calculator
     private JTextField display;
     private JButton addition;
     private JButton subtract;
     private JButton multiply;
     private JButton divide;
     private JButton mod;
     private JButton enter;
     private JButton [] digits;
     //End of components
     //Integer representations for the arithmetic operations needed
     private final static int ADD = 1;
     private final static int SUB = 2;
     private final static int MUL = 3;
     private final static int DIV = 4;
     private final static int MOD = 5;
     //ENd of arithmethic operations
     //Integer holding the operator that the user requested
     private int op;
     //Boolean variable to help perform the calculations
     private boolean firstFilled;
     private boolean clearScreen;
     //Constructor for the class
     public CalculatorFrame()
     contentPane=new Container();
     this.setSize(400,300); //sets the size of the frame
     this.setTitle("MIS 222 Calculator"); //sets the title of the frame
     //allows the "X" box in the upper right hand corner to close the entire application
     this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
     contentPane=this.getContentPane(); //gets the content pane
     //Methods
     addDisplay();
     addDigits();
     addDigitActionListeners();
     addOperation();
private void addDisplay()
     JLabel displayLab = new JLabel("Answer");
     JPanel north = new JPanel();
     north.add(displayLab);
     contentPane.add(north, "North");
//diplay was already declared above the constructor
     display = new JTextField(25);
//adding the components to the panel
     north.add(displayLab);
     north.add(display);
//adding the panel to frame's content pane
     contentPane.add(north, "North");
//Declaring the global digits array
private void addDigits()
     //Add 1 large panel to hold the 3 inner panels
     JPanel digPanel = new JPanel();
     //Set the panel's preferred size so that it will keep everything in line
     digPanel.setPreferredSize(new Dimension(200, 275));
     //Initialize the top 3 digits' JPanel and set its preferrd size
     JPanel topDigits = new JPanel();
     topDigits.setPreferredSize(new Dimension(200,60));
     //Initialize the middle 2 digits' JPanel and set its preferred size
     JPanel midDigits = new JPanel();
     midDigits.setPreferredSize(new Dimension(200,60));
     //Initialize the bottom digits' JPanel and set its preferred size
     JPanel botDigits = new JPanel();
     botDigits.setPreferredSize(new Dimension(200, 75));
     //Initialize the JButton array
     digits = new JButton[11];
     //Initialize each of the top Panel's digit buttons, and add it to the top panel
     for(int i=1; i<4; i++)
          String lab=(new Integer(i)).toString();
          digits=new JButton(lab);
          topDigits.add(digits[i]);
          //Adding the top Digit Panel to the overall digit panel
          digPanel.add(topDigits, BorderLayout.CENTER);
          //Adding the middle Digit Panel to the overall digit panel
          digPanel.add(midDigits, BorderLayout.CENTER);
          //Adding the bottom Digit Panel to the overall digit panel
          digPanel.add(botDigits, BorderLayout.CENTER);
          //Add the overall digit Panel to the Frame's contentpane
          contentPane.add(digPanel, BorderLayout.CENTER);
          //Method created to add the DigitAction Listeners
          addDigitActionListeners();
//Method created to add all of the DigitActionListeners
private void addDigitActionListeners()
          for(int i=0; i<10; i++)
               digits[i].addActionListener(new DigitActionListener(i));
          digits[10].addActionListener(new DigitActionListener("."));
//DigitActionListener class
public class DigitActionListener implements ActionListener
     private String myNum;
     public DigitActionListener(int num)
          myNum=""+num;
     public DigitActionListener(String num)
          myNum=num;
     public void actionPerformed(ActionEvent e)
          if(display.getText().equals("Please enter a valid number")|| clearScreen)
               clearScreen=false;
               display.setText("");
//OperatorActionListener class
public void OpActionListener implements ActionListener
     private int myOpNum;
     public OpActionListener(int op)
          myOpNum=op;
     public void actionPerformed(ActionEvent e)
     {  //Checks to see if the user has already enterd a number
          if(!firstFilled)
          try{
               //Parse the number entered
               String number=display.getText();
               dNum1=Double.parseDouble(number);
               //Sets the flag for the firstFilled to true
               firstFilled=true
               //Sets the op variable so when the "Enter" button is pressed, it will know which operation to perform
               op=myOpNum;
               //Clears the textbox
               display.setText("");
               catch(Exception er)
                    display.setText("Please enter a valid number");
     //This is the second number being entered
          else{
               try{
                    String number=display.getText();
                    String result;
                    dNum2=Double.parseDouble(number);
                    firstFilled=true;
                    op=myOpNum;
                    display.setText("");
               catch(Exception er)
                    display.setText("Please enter a valid number");
private void addOperation()
     JPanel opPanel=new JPanel();
     opPanel.setPreferredSize(new Dimension(75,200));
     JButton clear = new JButton("C");
     JButton addition = new JButton("+");
     JButton subtraction = new JButton("-");
     JButton multiply = new JButton("*");
     JButton divide = new JButton("/");
     JButton mod = new JButton("%");
     JButton enter = new JButton("Enter");
     addition.addActionListener(new OpActionListener(ADD));
     subtraction.addActionListener(new OpActionListener(SUB));
     multiply.addActionListener(new OpActionListener(MUL));
     divide.addActionListener(new OpActionListener(DIV));
     mod.addActionListener(new OpActionListener(MOD));
     clear.addActionListener(new ActionListener()
          public void actionPerformed(ActionEvent e)
               display.setText("");
               firstFilled=false;
     enter.addActionListener(new ActionListener()
          public void actionPerformed(ActionEvent e)
               double result;
               String answer="";
               String number = display.getText();
               dNum2 = Double.parseDouble(number);
               dNum1=Double.parseDouble(number);
               switch(op)
                    case ADD:
                         result = dNum1 + dNum2;
                         break;
                    case SUB:
                         result = dNum1 - dNum2;
                         break;
                    case MUL:
                         result = dNum1 * dNum2;
                         break;
                    case DIV:
                         result = dNum1 / dNum2;
                         break;
                    default:
                         result= -1.0;
                         break;
                    if(result==(int)result)
                         answer=(new Integer((int)result)).toString();
                    else
                         answer=(new Double(result)).toString();
                    display.setText(answer);
                    clearScreen=true;
                    firstFilled=false;
                    dNum1=0;
                    dNum2=0;
          opPanel.add(clear);
          opPanel.add(addition);
          opPanel.add(subtraction);
          opPanel.add(multiply);
          opPanel.add(divide);
          opPanel.add(mod);
          opPanel.add(enter);
          contentPane.add(opPanel, "East");
     //Creating the frame object
     public class CalculatorMain
          public void main(String[] args)
               CalculatorFrame cf=new CalculatorFrame();
               cf.show();
ERRORS THAT I HAVE!!:
javac calculatorframe.javacalculatorframe.java:150: '(' expected
public void OpActionListener implements ActionListener
^
calculatorframe.java:7: class CalculatorFrame is public, should be declared in a file named CalculatorFrame.java
public class CalculatorFrame extends JFrame
^
calculatorframe.java:54: cannot resolve symbol
symbol : method addOperation ()
location: class CalculatorFrame
addOperation();
^
3 errors
>

Answer 1

Hi, actually it's all written there:
>
ERRORS THAT I HAVE!!:
javac calculatorframe.javacalculatorframe.java:150: '(' expected
public void OpActionListener implements
ActionListenerpublic void ... is part of a possible method signature. That's probably why the compiler expects '(' as this is need for a method.
To define a class use:
public class ... (or better: private class ..., if the class is not used outside of this file.
^
calculatorframe.java:7: class CalculatorFrame is
public, should be declared in a file named
CalculatorFrame.java
public class CalculatorFrame extends JFrame
^As it says, you defined a class CalculatorFrame in a file calculatorframe.java. But the file name should be the same as the class name (case sensitive). Java classes should start with capital letters, so rename the file to:
CalculatorFrame.java
calculatorframe.java:54: cannot resolve symbol
symbol : method addOperation ()
location: class CalculatorFrame
addOperation();
^
3 errors
>You didn't declare the method 'addOperation' (-> cannot resolve symbol; which simbol: method addOperation (); where: location: class CalculatorFrame; you see it's all there)
Note there is a method called 'addOperation' in the class OpActionListener, but not in CalculatorFrame.
Note I didn't read the code, just the error messages. I hope this helps.
-Puce