I have created a file that reads in a text file for a combo box which are exams assignments and quizes. I then have a a textfield that places the scores with the selected item in the combo box. I then add the info to a text area. I am trying to extract the grads for each of the items (quizes, assignments, etc.) so I can have the average of each item. I then need to graph this information.

this is the part of my code i am having trouble with:

/*

* To change this template, choose Tools | Templates * and open the template in the editor. */

/* * Login.java * * Created on Nov 3, 2011, 5:18:25 PM */ package assignment3;

import java.io.File; import java.io.FileOutputStream; import javax.swing.JOptionPane; import java.io.BufferedReader; import java.io.FileReader;

/** * * @author Owner */ public class MainScreen extends javax.swing.JFrame {

/** Creates new form Login */
public MainScreen() 
{
    initComponents();

    try
    {
     //Read in files
    BufferedReader br = new BufferedReader(new FileReader("grades.txt"));
    //Declare String variable called line
    String line;
    //read in information off of the text file
    while((line=br.readLine()) !=null)
    {
        //add text to list
        cboxGrades.addItem(line);

    }
    }
    catch(Exception e)
    {
        JOptionPane.showMessageDialog(null, "File Not Found","Error",JOptionPane.ERROR_MESSAGE);
        System.exit(0);
    }


}

/** This method is called from within the constructor to
 * initialize the form.
 * WARNING: Do NOT modify this code. The content of this method is
 * always regenerated by the Form Editor.
 */
@SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">                          
private void initComponents() {

    lbltitle = new javax.swing.JLabel();
    lblStudentID = new javax.swing.JLabel();
    txtStudentID = new javax.swing.JTextField();
    lblStudentName = new javax.swing.JLabel();
    txtStudentName = new javax.swing.JTextField();
    cboxGrades = new javax.swing.JComboBox();
    lblGrades = new javax.swing.JLabel();
    txtGrades = new javax.swing.JTextField();
    btnSave = new javax.swing.JButton();
    btnClear = new javax.swing.JButton();
    btnGraph = new javax.swing.JButton();
    jScrollPane1 = new javax.swing.JScrollPane();
    areaGrades = new javax.swing.JTextArea();

    setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

    lbltitle.setFont(new java.awt.Font("Tahoma", 1, 14));
    lbltitle.setText("Main Screen");

    lblStudentID.setText("Studen ID");

    txtStudentID.setColumns(5);
    txtStudentID.setToolTipText("Enter Student Name");
    txtStudentID.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            txtStudentIDActionPerformed(evt);
        }
    });

    lblStudentName.setText("Student Name");

    txtStudentName.setColumns(5);
    txtStudentName.setToolTipText("Enter Student name");
    txtStudentName.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            txtStudentNameActionPerformed(evt);
        }
    });

    cboxGrades.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            cboxGradesActionPerformed(evt);
        }
    });

    lblGrades.setText("Grades");

    txtGrades.setToolTipText("Enter in Assignments");
    txtGrades.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            txtGradesActionPerformed(evt);
        }
    });
    txtGrades.addKeyListener(new java.awt.event.KeyAdapter() {
        public void keyPressed(java.awt.event.KeyEvent evt) {
            txtGradesKeyPressed(evt);
        }
    });

    btnSave.setText("Save");
    btnSave.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            btnSaveActionPerformed(evt);
        }
    });

    btnClear.setText("Clear");
    btnClear.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            btnClearActionPerformed(evt);
        }
    });

    btnGraph.setText("Graph");
    btnGraph.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            btnGraphActionPerformed(evt);
        }
    });

    areaGrades.setColumns(20);
    areaGrades.setRows(5);
    jScrollPane1.setViewportView(areaGrades);

    javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
    getContentPane().setLayout(layout);
    layout.setHorizontalGroup(
        layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGroup(layout.createSequentialGroup()
            .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                .addGroup(layout.createSequentialGroup()
                    .addGap(53, 53, 53)
                    .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                        .addComponent(lblStudentID)
                        .addGroup(layout.createSequentialGroup()
                            .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
                                .addGroup(javax.swing.GroupLayout.Alignment.LEADING, layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                                    .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                                        .addComponent(txtStudentID, javax.swing.GroupLayout.PREFERRED_SIZE, 57, javax.swing.GroupLayout.PREFERRED_SIZE)
                                        .addComponent(lblStudentName)
                                        .addComponent(lblGrades)
                                        .addComponent(txtStudentName, javax.swing.GroupLayout.DEFAULT_SIZE, 117, Short.MAX_VALUE))
                                    .addComponent(btnSave))
                                .addComponent(cboxGrades, javax.swing.GroupLayout.Alignment.LEADING, javax.swing.GroupLayout.PREFERRED_SIZE, 117, javax.swing.GroupLayout.PREFERRED_SIZE)
                                .addComponent(txtGrades, javax.swing.GroupLayout.Alignment.LEADING, javax.swing.GroupLayout.PREFERRED_SIZE, 40, javax.swing.GroupLayout.PREFERRED_SIZE))
                            .addGap(66, 66, 66)
                            .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
                                .addGroup(layout.createSequentialGroup()
                                    .addComponent(btnGraph)
                                    .addGap(100, 100, 100)
                                    .addComponent(btnClear))
                                .addComponent(jScrollPane1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
                            .addGap(77, 77, 77))))
                .addGroup(layout.createSequentialGroup()
                    .addGap(216, 216, 216)
                    .addComponent(lbltitle)))
            .addContainerGap())
    );
    layout.setVerticalGroup(
        layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGroup(layout.createSequentialGroup()
            .addComponent(lbltitle)
            .addGap(23, 23, 23)
            .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
                .addGroup(layout.createSequentialGroup()
                    .addComponent(lblStudentID)
                    .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                    .addComponent(txtStudentID, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                    .addComponent(lblStudentName)
                    .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                    .addComponent(txtStudentName, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                    .addComponent(lblGrades)
                    .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                    .addComponent(cboxGrades, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
                .addComponent(jScrollPane1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
            .addGap(18, 18, 18)
            .addComponent(txtGrades, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
            .addGap(18, 18, 18)
            .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                .addComponent(btnSave)
                .addComponent(btnClear, javax.swing.GroupLayout.PREFERRED_SIZE, 23, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addComponent(btnGraph))
            .addContainerGap(95, Short.MAX_VALUE))
    );

    pack();
}// </editor-fold>                        

private void txtStudentIDActionPerformed(java.awt.event.ActionEvent evt) {                                             
    // TODO add your handling code here:

    if (txtStudentID.getText().contentEquals(" ")) 
    {
        //Error message to show that Student ID is empty
        JOptionPane.showMessageDialog(this, "You did not enter an ID", "Error", JOptionPane.ERROR_MESSAGE);
    }
    if (txtStudentID.getText().length() > 5) 
    {
        //Error message for Student ID being longer than 5
        JOptionPane.showMessageDialog(this, "Your ID is too long!", "Error", JOptionPane.ERROR_MESSAGE);
    }
    //Checks to see if Student ID is empty

    try 
    {
        //Changes student ID to an Integer
        int number = Integer.parseInt(this.txtStudentID.getText());
    } 
    //catches exception for non valid number
    catch (Exception e) 
    {
        //error message to show numbers only
        JOptionPane.showMessageDialog(this, "Please enter in numbers only", "Error", JOptionPane.ERROR_MESSAGE);
        txtStudentID.setText(null);
    }
}                                            

private void txtStudentNameActionPerformed(java.awt.event.ActionEvent evt) {                                               
    // TODO add your handling code here:

    if(txtStudentName.getText() == null)
    {
        JOptionPane.showMessageDialog(null, "Invalid name","Error Message",JOptionPane.ERROR_MESSAGE);
    }


}                                              

private void txtGradesActionPerformed(java.awt.event.ActionEvent evt) {                                          
    // TODO add your handling code here:

    int scores = Integer.parseInt(txtGrades.getText());
    if(scores > 100)
    {
        JOptionPane.showMessageDialog(null, "Invalid Grade, try again","Error",JOptionPane.ERROR_MESSAGE);
    }
    String list = cboxGrades.getSelectedItem()+":  "+txtGrades.getText()+"\n";
    areaGrades.append(list);
    txtGrades.setText(null);



    if(cboxGrades.getSelectedItem().equals("Exam 1"))
    cboxGrades.removeItemAt(1);

    if(cboxGrades.getSelectedItem().equals("Exam 2"))

    cboxGrades.removeItemAt(1);
    if(cboxGrades.getSelectedItem().equals("Exam 3"))

    cboxGrades.removeItemAt(1);
    if(cboxGrades.getSelectedItem().equals("Assignment 1"))

    cboxGrades.removeItemAt(1);
    if(cboxGrades.getSelectedItem().equals("Assignment 2"))

    cboxGrades.removeItemAt(1);
    if(cboxGrades.getSelectedItem().equals("Assignment 3"))

    cboxGrades.removeItemAt(1);
    if(cboxGrades.getSelectedItem().equals("Quiz 1"))

    cboxGrades.removeItemAt(1);
    if(cboxGrades.getSelectedItem().equals("Quiz 2"))

    cboxGrades.removeItemAt(1);
    if(cboxGrades.getSelectedItem().equals("Quiz 3"))

    cboxGrades.setSelectedItem(1);
    if(cboxGrades.getSelectedItem().equals("Final Exam"))

    cboxGrades.removeItemAt(1);



}                                         

private void btnSaveActionPerformed(java.awt.event.ActionEvent evt) {                                        
    // TODO add your handling code here:

    try
    {

        String content = new String();            
        content = txtStudentID.getText().toString()+"   "+txtStudentName.getText().toString()+
                         "  "+areaGrades.getText().toString();

        File file = new File("Student.txt");

        if(!file.exists())
        {
            file.createNewFile();
        }
        FileOutputStream fop = new FileOutputStream(file);
        fop.write(content.getBytes());
        fop.flush();
        fop.close();

        JOptionPane.showMessageDialog(null, "Data was added to the file!! "+file);
    }
    catch(Exception e)
    {
        JOptionPane.showMessageDialog(null, "The Data was not added to the file!","Error",JOptionPane.ERROR_MESSAGE);
    }


}                                       

private void btnClearActionPerformed(java.awt.event.ActionEvent evt) {                                         
    // TODO add your handling code here:

    txtStudentID.setText(null);
    txtStudentName.setText(null);
    txtGrades.setText(null);
    areaGrades.setText(null);
    try
    {
     //Read in files
    BufferedReader br = new BufferedReader(new FileReader("grades.txt"));
    //Declare String variable called line
    String line;
    //read in information off of the text file
    while((line=br.readLine()) !=null)
    {
        //add text to list
        cboxGrades.addItem(line);

    }
    }
    catch(Exception e)
    {
        JOptionPane.showMessageDialog(null, "File Not Found","Error",JOptionPane.ERROR_MESSAGE);
        System.exit(0);
    }



}                                        

private void cboxGradesActionPerformed(java.awt.event.ActionEvent evt) {                                           
    // TODO add your handling code here 

}                                          

private void btnGraphActionPerformed(java.awt.event.ActionEvent evt) {                                         
    // TODO add your handling code here:
    System.out.println("Index\tValue");
    String myarray[] = null;
    for(int i = 0; i < myarray.length;i++)
    {
        myarray[] = areaGrades.getText().toString();
    }



}                                        

private void txtGradesKeyPressed(java.awt.event.KeyEvent evt) {                                     
    // TODO add your handling code here:

}                                    

/**
 * @param args the command line arguments
 */
public static void main(String args[]) {
    /* Set the Nimbus look and feel */
    //<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
    /* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
     * For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html 
     */
    try {
        for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
            if ("Nimbus".equals(info.getName())) {
                javax.swing.UIManager.setLookAndFeel(info.getClassName());
                break;
            }
        }
    } catch (ClassNotFoundException ex) {
        java.util.logging.Logger.getLogger(MainScreen.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    } catch (InstantiationException ex) {
        java.util.logging.Logger.getLogger(MainScreen.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    } catch (IllegalAccessException ex) {
        java.util.logging.Logger.getLogger(MainScreen.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    } catch (javax.swing.UnsupportedLookAndFeelException ex) {
        java.util.logging.Logger.getLogger(MainScreen.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    }
    //</editor-fold>

    /* Create and display the form */
    java.awt.EventQueue.invokeLater(new Runnable() {

        @Override
        public void run() {
            new MainScreen().setVisible(true);

        }
    });
}


// Variables declaration - do not modify                     
private javax.swing.JTextArea areaGrades;
private javax.swing.JButton btnClear;
private javax.swing.JButton btnGraph;
private javax.swing.JButton btnSave;
private javax.swing.JComboBox cboxGrades;
private javax.swing.JScrollPane jScrollPane1;
private javax.swing.JLabel lblGrades;
private javax.swing.JLabel lblStudentID;
private javax.swing.JLabel lblStudentName;
private javax.swing.JLabel lbltitle;
private javax.swing.JTextField txtGrades;
private javax.swing.JTextField txtStudentID;
private javax.swing.JTextField txtStudentName;
// End of variables declaration

}