Need help with assignment for class. its for my high school project :(

Question

i really need help, my problem is that with my code i cannot get the "previous", "done" and "next" buttons to work.they cannot seem to find the items from each other. so could someone look at those buttons in the code and tell me how to fix please? the code is as follows:
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class GradeCalculator extends JFrame {
     private JTextField gradeA = new JTextField(3);
     private JTextField gradeB = new JTextField(3);
     private JTextField gradeC = new JTextField(3);
     private JTextField gradeD = new JTextField(3);
     private JTextField gradeE = new JTextField(3);
     private JTextField studentsName = new JTextField(15);
     private JTextField assignmentOne = new JTextField(5);
     private JTextField assignmentTwo = new JTextField(5);
     private JTextField assignmentThree = new JTextField(5);
     private JTextField examOne = new JTextField(5);
     private JTextField examTwo = new JTextField(5);
     private JTextArea textOutput;
     private JPanel buttonJPanel;
     public GradeCalculator(){
          JMenu fileMenu = new JMenu("File");
          JMenuItem aboutItem = new JMenuItem( "About" );
fileMenu.add( aboutItem );
aboutItem.addActionListener(
new ActionListener()
public void actionPerformed( ActionEvent event )
JOptionPane.showMessageDialog( GradeCalculator.this,
"Grade Calculator Version 1.00. \nMade by Carlson Smith.\nSchool: Pre-University\nSubject: Cape Computer Science.",
"About", JOptionPane.PLAIN_MESSAGE );
          JMenuItem exitItem = new JMenuItem( "Exit" );
fileMenu.add( exitItem );
exitItem.addActionListener(
new ActionListener()
public void actionPerformed( ActionEvent event )
System.exit( 0 );
          JMenuBar bar = new JMenuBar();
          setJMenuBar(bar);
          bar.add(fileMenu);     
          JTabbedPane tabbedPane = new JTabbedPane();
          buttonJPanel = new JPanel();
          buttonJPanel.setLayout(new GridLayout(1,2));
          JButton ok = new JButton("OK");
          ok.addActionListener(new OkBtnListener());
          JButton edit = new JButton("EDIT");
          edit.addActionListener(new EditBtnListener());
          /**JButton previous = new JButton("PREVIOUS");
          previous.addActionListener(new PreviousBtnListener());
          JButton done = new JButton("DONE");
          done.addActionListener(new DoneBtnListener());
          JButton next = new JButton("NEXT");
          next.addActionListener(new NextBtnListener());
          JPanel contentPane = new JPanel();
          contentPane.setLayout(new FlowLayout());
          contentPane.add(new JLabel("Grade A")/**,BorderLayout.NORTH*/);
          contentPane.add(gradeA/**,BorderLayout.NORTH*/);
          contentPane.add(new JLabel("Grade B")/**,BorderLayout.WEST*/);
          contentPane.add(gradeB/**,BorderLayout.WEST*/);
          contentPane.add(new JLabel("Grade C")/**,BorderLayout.WEST*/);
          contentPane.add(gradeC/**,BorderLayout.WEST*/);
          contentPane.add(new JLabel("Grade D")/**,BorderLayout.WEST*/);
          contentPane.add(gradeD/**,BorderLayout.WEST*/);
          contentPane.add(new JLabel("Grade E")/**,BorderLayout.WEST*/);
          contentPane.add(gradeE/**,BorderLayout.WEST*/);
          tabbedPane.addTab("Grade Entry Tab", null, contentPane, "Grade Tab");
          //contentPane.add(ok,BorderLayout.WEST);
          //contentPane.add(edit,BorderLayout.WEST);
          buttonJPanel.add(ok);
          buttonJPanel.add(edit);
          contentPane.add(buttonJPanel, BorderLayout.WEST);
          JPanel content = new JPanel();
          content.setLayout(new FlowLayout());
          content.add(new JLabel("Student's Name")/**,BorderLayout.EAST*/);
          content.add(studentsName/**,BorderLayout.EAST*/);
          content.add(new JLabel("Assignment 1 score:")/**,BorderLayout.EAST*/);
          content.add(assignmentOne/**,BorderLayout.EAST*/);
          content.add(new JLabel("Assignment 2 score:")/**,BorderLayout.EAST*/);
          content.add(assignmentTwo/**,BorderLayout.EAST*/);
          content.add(new JLabel("Assignment 3 score:")/**,BorderLayout.EAST*/);
          content.add(assignmentThree/**,BorderLayout.EAST*/);
          content.add(new JLabel("Exam 1 score:")/**,BorderLayout.EAST*/);
          content.add(examOne/**,BorderLayout.EAST*/);
          content.add(new JLabel("Exam 2 score:")/**,BorderLayout.EAST*/);
          content.add(examTwo/**,BorderLayout.EAST*/);
          //content.add(previous,BorderLayout.EAST);
          //content.add(done,BorderLayout.EAST);
          //content.add(next,BorderLayout.EAST);
          Box box = Box.createVerticalBox();
          String output = "test";
          String outputTwo = output;
          textOutput = new JTextArea(outputTwo,10,30);
          box.add(new JScrollPane(textOutput));
          textOutput.setEditable(false);
          content.add(box,BorderLayout.SOUTH);
          tabbedPane.addTab("Calculator Tab", null, content, "Calculation & Output Tab");
          setContentPane(tabbedPane);
          pack();
          setTitle("Grade Calculator");
          setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
          setLocationRelativeTo(null);
          class OkBtnListener implements ActionListener{
               public void actionPerformed(ActionEvent e){
                    String gradeAA = gradeA.getText();
                    double gradA = Double.parseDouble(gradeAA);
                    gradeA.setText(" "+gradA);
                    String gradeBB = gradeB.getText();
                    double gradB = Double.parseDouble(gradeBB);
                    gradeB.setText(" "+gradB);
                    String gradeCC = gradeC.getText();
                    double gradC = Double.parseDouble(gradeCC);
                    gradeC.setText(" "+gradC);
                    String gradeDD = gradeD.getText();
                    double gradD = Double.parseDouble(gradeDD);
                    gradeD.setText(" "+gradD);
                    String gradeEE = gradeE.getText();
                    double gradE = Double.parseDouble(gradeEE);
                    gradeE.setText(" "+gradE);
                    gradeA.setEditable(false);
                    gradeB.setEditable(false);
                    gradeC.setEditable(false);
                    gradeD.setEditable(false);
                    gradeE.setEditable(false);
          class EditBtnListener implements ActionListener{
               public void actionPerformed(ActionEvent e){
                    gradeA.setEditable(true);
                    gradeB.setEditable(true);
                    gradeC.setEditable(true);
                    gradeD.setEditable(true);
                    gradeE.setEditable(true);
          /**class PreviousBtnListener implements ActionListener{
               public void actionPerformed(ActionEvent e){
                    if (i <= 0){
                         i = 0;
                    }else if(i > 0){
                         i = i-1;
          class DoneBtnListener implements ActionListener{
               public void actionPerformed(ActionEvent e){
                    output = "Results \n";
                    output+= studentName[i]+" Assignment Average = "+averageO[i]+" Exam Average = "+averageT[i]+" Overall average = ";
                    output+= tAverage[i]+" Letter Grade = "+letterGrade;
          class NextBtnListener implements ActionListener{
               public void actionPerformed(ActionEvent e){
                    String [] studentName = new String [40];
                    double [] assignOne = new double [40];
                    double [] assignTwo = new double [40];
                    double [] assignThree = new double [40];
                    double [] gradeOne = new double [40];
                    double [] gradeTwo = new double [40];
                    double [] averageO = new double [40];
                    double [] averageT = new double [40];
                    double [] tAverage = new double [40];
                    char [] letterGrade = new char [40];
                    double max = 0;
                    double min = 100;
                    int i = 0;
                    while(i < studentName.length){
                         studentName[i] = studentsName.getText();
                         studentsName.setText(studentName[i]);
                         String aOne = assignmentOne.getText();
                         assignOne[i] = Double.parseDouble(aOne);
                         assignmentOne.setText(assignOne[i]);
                         String aTwo = assignmentTwo.getText();
                         assignTwo[i] = Double.parseDouble(aTwo);
                         assignmentTwo.setText(assignTwo[i]);
                         String aThree = assignmentThree.getText();
                         assignThree[i] = Double.parseDouble(aThree);
                         assignmentThree.setText(assignThree[i]);
                         String gOne = examOne.getText();
                         gradeOne[i] = Double.parseDouble(gOne);
                         examOne.setText(gradeOne[i]);
                         String gTwo = examTwo.getText();
                         gradeTwo = Double.parseDouble(gTwo);
                         examTwo.setText(gradeTwo[i]);
                         averageO[i] = (assignOne[i]+assignTwo[i]+assignThree[i])/3;
                         averageT[i] = (gradeOne[i]+gradeTwo[i])/2;
                         tAverage[i] = (averageO[i]+averageT[i])/2;
                         if (tAverage[i] >= gradeA){
                              letterGrade[i] = 'A';
                         }else if(tAverage[i] >= gradeB){
                              letterGrade[i] = 'B';
                         }else if(tAverage[i] >= gradeC){
                              letterGrade[i] = 'C';
                         }else if(tAverage[i] >= gradeD){
                              letterGrade[i] = 'D';
                         }else if(tAverage[i] <= gradeE){
                              letterGrade[i] = 'E';
          public static void main(String[]args){
               GradeCalculator calWindow = new GradeCalculator();
               calWindow.setVisible(true);

Answer 1

i have to apologize to jittei for the misunderstand i do not know which defination of terms is for which line of code but i know what they do, to solve the problem i have actually made another class in the workspace file called students and now all the bottons work, all i have to do now is properly arrange and put in some additional lines of code and it will be completed. teacher gave me the idea of putting in a new class to help in calling codes from other subclasses in the main program. ah well guess non of you could think of that thanks for the help-ish and hope yall will atleast try to be nice to new people that come in the room. the new coding is:
of course all the commented out lines are not being used in the program anymore but just there till i have the program working with everything in it runs and performs the actions required now though ^_^
*Group CAPE Computer Science 2007/8
*GradeCalculator.java
*@author Carlson Smith
*@version 3.01          07/02/2008
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class GradeCalculator extends JFrame {
     private JTextField gradeA = new JTextField(3);
     private JTextField gradeB = new JTextField(3);
     private JTextField gradeC = new JTextField(3);
     private JTextField gradeD = new JTextField(3);
     private JTextField gradeE = new JTextField(3);
     private JTextField studentsName = new JTextField(15);
     private JTextField assignmentOne = new JTextField(5);
     private JTextField assignmentTwo = new JTextField(5);
     private JTextField assignmentThree = new JTextField(5);
     private JTextField examOne = new JTextField(5);
     private JTextField examTwo = new JTextField(5);
     private JTextArea  textOutput;
     private JPanel buttonJPanel;
     private JPanel buttonJPanelTwo;
     private Student [] students = new Student[40];
     private int current = 0;
     private String output;
     public GradeCalculator(){
          JMenu fileMenu = new JMenu("File");
          JMenuItem aboutItem = new JMenuItem( "About" );
          for (int i=0;i<40;i++){
               students[i] = new Student("");
        fileMenu.add( aboutItem );
        aboutItem.addActionListener(
           new ActionListener()
              public void actionPerformed( ActionEvent event )
                 JOptionPane.showMessageDialog( GradeCalculator.this,
                    "Grade Calculator Version 1.00. \nMade by Carlson Smith.\nSchool: Pre-University\nSubject: Cape Computer Science.",
                    "About", JOptionPane.PLAIN_MESSAGE );
          JMenuItem exitItem = new JMenuItem( "Exit" ); 
        fileMenu.add( exitItem );
        exitItem.addActionListener(
           new ActionListener()
              public void actionPerformed( ActionEvent event )
                 System.exit( 0 );
          JMenuBar bar = new JMenuBar();
          setJMenuBar(bar);
          bar.add(fileMenu);     
          JTabbedPane tabbedPane = new JTabbedPane();
          buttonJPanel = new JPanel();
          buttonJPanel.setLayout(new GridLayout(1,2));
          JButton ok = new JButton("OK");
          ok.addActionListener(new OkBtnListener());
          JButton edit = new JButton("EDIT");
          edit.addActionListener(new EditBtnListener());
          buttonJPanelTwo = new JPanel();
          buttonJPanelTwo.setLayout(new GridLayout(1,3));
          JButton previous = new JButton("PREVIOUS");
          previous.addActionListener(new PreviousBtnListener());
          JButton done = new JButton("DONE");
          done.addActionListener(new DoneBtnListener());
          JButton next = new JButton("NEXT");
          next.addActionListener(new NextBtnListener());
          JPanel contentPane = new JPanel();
          contentPane.setLayout(new FlowLayout());
          contentPane.add(new JLabel("Grade A")/**,BorderLayout.NORTH*/);
          contentPane.add(gradeA/**,BorderLayout.NORTH*/);
          contentPane.add(new JLabel("Grade B")/**,BorderLayout.WEST*/);
          contentPane.add(gradeB/**,BorderLayout.WEST*/);
          contentPane.add(new JLabel("Grade C")/**,BorderLayout.WEST*/);
          contentPane.add(gradeC/**,BorderLayout.WEST*/);
          contentPane.add(new JLabel("Grade D")/**,BorderLayout.WEST*/);
          contentPane.add(gradeD/**,BorderLayout.WEST*/);
          contentPane.add(new JLabel("Grade E")/**,BorderLayout.WEST*/);
          contentPane.add(gradeE/**,BorderLayout.WEST*/);
          tabbedPane.addTab("Grade Entry Tab", null, contentPane, "Grade Tab");
          //contentPane.add(ok,BorderLayout.WEST);
          //contentPane.add(edit,BorderLayout.WEST);
          buttonJPanel.add(ok);
          buttonJPanel.add(edit);
          contentPane.add(buttonJPanel, BorderLayout.WEST);
          JPanel content = new JPanel();
          content.setLayout(new FlowLayout());
          content.add(new JLabel("Student's Name")/**,BorderLayout.EAST*/);
          content.add(studentsName/**,BorderLayout.EAST*/);
          content.add(new JLabel("Assignment 1 score:")/**,BorderLayout.EAST*/);
          content.add(assignmentOne/**,BorderLayout.EAST*/);
          content.add(new JLabel("Assignment 2 score:")/**,BorderLayout.EAST*/);
          content.add(assignmentTwo/**,BorderLayout.EAST*/);
          content.add(new JLabel("Assignment 3 score:")/**,BorderLayout.EAST*/);
          content.add(assignmentThree/**,BorderLayout.EAST*/);
          content.add(new JLabel("Exam 1 score:")/**,BorderLayout.EAST*/);
          content.add(examOne/**,BorderLayout.EAST*/);
          content.add(new JLabel("Exam 2 score:")/**,BorderLayout.EAST*/);
          content.add(examTwo/**,BorderLayout.EAST*/);
          //content.add(previous,BorderLayout.EAST);
          //content.add(done,BorderLayout.EAST);
          //content.add(next,BorderLayout.EAST);
          buttonJPanelTwo.add(previous);
          buttonJPanelTwo.add(done);
          buttonJPanelTwo.add(next);
          content.add(buttonJPanelTwo, BorderLayout.EAST);
          Box box = Box.createVerticalBox();
          //String outputTwo = output;
          //textOutput.setText(output);
          textOutput = new JTextArea(output,10,30);
          box.add(new JScrollPane(textOutput));
          //textOutput.setEditable(true);
          content.add(box,BorderLayout.SOUTH);
          tabbedPane.addTab("Calculator Tab", null, content, "Calculation & Output Tab");
          setContentPane(tabbedPane);
          pack();
          setTitle("Grade Calculator");
          setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
          setLocationRelativeTo(null);
          class OkBtnListener implements ActionListener{
               public void actionPerformed(ActionEvent e){
                    String gradeAA = gradeA.getText();
                    double gradA = Double.parseDouble(gradeAA);
                    gradeA.setText(" "+gradA);
                    String gradeBB = gradeB.getText();
                    double gradB = Double.parseDouble(gradeBB);
                    gradeB.setText(" "+gradB);
                    String gradeCC = gradeC.getText();
                    double gradC = Double.parseDouble(gradeCC);
                    gradeC.setText(" "+gradC);
                    String gradeDD = gradeD.getText();
                    double gradD = Double.parseDouble(gradeDD);
                    gradeD.setText(" "+gradD);
                    String gradeEE = gradeE.getText();
                    double gradE = Double.parseDouble(gradeEE);
                    gradeE.setText(" "+gradE);
                    gradeA.setEditable(false);
                    gradeB.setEditable(false);
                    gradeC.setEditable(false);
                    gradeD.setEditable(false);
                    gradeE.setEditable(false);
          class EditBtnListener implements ActionListener{
               public void actionPerformed(ActionEvent e){
                    gradeA.setEditable(true);
                    gradeB.setEditable(true);
                    gradeC.setEditable(true);
                    gradeD.setEditable(true);
                    gradeE.setEditable(true);
          class PreviousBtnListener implements ActionListener{
               public void actionPerformed(ActionEvent e){
                    Student currentStudent = students[current];
                    currentStudent.setStudentName(studentsName.getText());          
                    currentStudent.setAssignOne(Double.parseDouble(assignmentOne.getText()));
                    currentStudent.setAssignTwo(Double.parseDouble(assignmentTwo.getText()));
                    currentStudent.setAssignThree(Double.parseDouble(assignmentThree.getText()));
                    currentStudent.setExamOneGrade(Double.parseDouble(examOne.getText()));
                    currentStudent.setExamTwoGrade(Double.parseDouble(examTwo.getText()));
                    currentStudent = students[current];
                    if (current <= 0){
                         current = 0;
                    }else if(current > 0){
                         current = current-1;
                    refresh();               
                    System.out.println(current);
          class DoneBtnListener implements ActionListener{
               public void actionPerformed(ActionEvent e){
                    Student currentStudent = students[current];
                    //output = "Result \n";
                    output = currentStudent.getStudentName()+". Assignment Average = "+currentStudent.getAverage()+". Exam Average = "+currentStudent.getExamAverage()+". Overall average = ";
                    output+= currentStudent.getTotalAverage()/**+" Letter Grade = "+letterGrade[current]*/;
                    textOutput.setText(output);
                    System.out.println(output);
                    currentStudent = students[current];
          class NextBtnListener implements ActionListener{
               public void actionPerformed(ActionEvent e){
//                    String [] studentName = new String [40];
//                    double [] assignOne = new double [40];
//                    double [] assignTwo = new double [40];
//                    double [] assignThree = new double [40];
//                    double [] gradeOne = new double [40];
//                    double [] gradeTwo = new double [40];
//                    double [] averageO = new double [40];
//                    double [] averageT = new double [40];
//                    double [] tAverage = new double [40];
//                    char [] letterGrade = new char [40];
                    //double max = 0;
                    //double min = 100;
                    Student currentStudent = students[current];
                    currentStudent.setStudentName(studentsName.getText());
                    currentStudent.setAssignOne(Double.parseDouble(assignmentOne.getText()));
                    currentStudent.setAssignTwo(Double.parseDouble(assignmentTwo.getText()));
                    currentStudent.setAssignThree(Double.parseDouble(assignmentThree.getText()));
                    currentStudent.setExamOneGrade(Double.parseDouble(examOne.getText()));
                    currentStudent.setExamTwoGrade(Double.parseDouble(examTwo.getText()));
//                    currentStudent = students[current];
                    current++;
                    refresh();
/**                    while(i < studentName.length){
                         String aOne = assignmentOne.getText();
                         assignOne[i] = Double.parseDouble(aOne);
                         assignmentOne.setText(" "+assignOne);
                         String aTwo = assignmentTwo.getText();
                         assignTwo[i] = Double.parseDouble(aTwo);
                         assignmentTwo.setText(" "+assignTwo[i]);
                         String aThree = assignmentThree.getText();
                         assignThree[i] = Double.parseDouble(aThree);
                         assignmentThree.setText(" "+assignThree[i]);
                         String gOne = examOne.getText();
                         gradeOne[i] = Double.parseDouble(gOne);
                         examOne.setText(" "+gradeOne[i]);
                         String gTwo = examTwo.getText();
                         gradeTwo[i] = Double.parseDouble(gTwo);
                         examTwo.setText(" "+gradeTwo[i]);
                         averageO[i] = (assignOne[i]+assignTwo[i]+assignThree[i])/3;
                         averageT[i] = (gradeOne[i]+gradeTwo[i])/2;
                         tAverage[i] = (averageO[i]+averageT[i])/2;
                         if (tAverage[i] >= Double.parseDouble(gradeA.getText())){
                              letterGrade[i] = 'A';
                         }else if(tAverage[i] >= Double.parseDouble(gradeB.getText())){
                              letterGrade[i] = 'B';
                         }else if(tAverage[i] >= Double.parseDouble(gradeC.getText())){
                              letterGrade[i] = 'C';
                         }else if(tAverage[i] >= Double.parseDouble(gradeD.getText())){
                              letterGrade[i] = 'D';
                         }else if(tAverage[i] <= Double.parseDouble(gradeE.getText())){
                              letterGrade[i] = 'E';
          public void refresh(){
               Student currentStudent = students[current];
               studentsName.setText(currentStudent.getStudentName());
               assignmentOne.setText(currentStudent.getAssignOne()+"");
               assignmentTwo.setText(currentStudent.getAssignTwo()+"");
               assignmentThree.setText(currentStudent.getAssignThree()+"");
               examOne.setText(currentStudent.getExamOneGrade()+"");
               examTwo.setText(currentStudent.getExamTwoGrade()+"");
          public static void main(String[]args){
               GradeCalculator calWindow = new GradeCalculator();
               calWindow.setVisible(true);
Second class implemented./**
*Group CAPE Computer Science 2007/8
*Student.java
*@author Carlson Smith
*@version 3.01          07/02/2008
public class Student {
     private String studentName;
     private double assignOne;
     private double assignTwo;
     private double assignThree;
     private double examOneGrade;
     private double examTwoGrade;
     public Student(String sName){
          studentName = sName;     
     public String getStudentName(){
          return studentName;
     public double getAssignOne(){
          return assignOne;
     public double getAssignTwo(){
          return assignTwo;
     public double getAssignThree(){
          return assignThree;
     public double getExamOneGrade(){
          return examOneGrade;
     public double getExamTwoGrade(){
          return examTwoGrade;
     public void setStudentName(String sName){
          studentName = sName;
     public void setAssignOne(double assignOne){
          this.assignOne = assignOne;
     public void setAssignTwo(double assignTwo){
          this.assignTwo = assignTwo;
     public void setAssignThree(double assignThree){
          this.assignThree = assignThree;
     public void setExamOneGrade(double examOneGrade){
          this.examOneGrade = examOneGrade;
     public void setExamTwoGrade(double examTwoGrade){
          this.examTwoGrade = examTwoGrade;
     public double getAverage(){
          return (assignOne + assignTwo + assignThree)/3;
     public double getExamAverage(){
          return (examOneGrade + examTwoGrade)/2;
     public double getTotalAverage(){
          return (getAverage() + getExamAverage())/2;
this thread can be closed now. l8rz :P
Edited by: Jacal on Feb 10, 2008 7:28 AM