Hi i have to do a project and its due in like 2days and i cant figure out whats wrong with it!! I managed to get the project writing the info to the dat file, however it won't read it back. It's compiling fine, it's just for some reason the read method won't work and the next and back buttons won't work. I want it to read the info from the dat file to the textboxes and then be able to navigate through the files with the next and back buttons. I can't see a problem with the code and since it's compiling ok I don't have a clue. Any help would be appreciated!! Heres the code: Code: import java.io.*; import java.awt.*; import javax.swing.*; import javax.swing.border.*; import java.awt.event.*; import java.io.RandomAccessFile; //we got the code for this page from Daniel Liang's book Java:How to Program chapter on RAF-Address book example public class IS2216 extends JFrame { private static int FNameSize = 15; private static int SNameSize = 20; private static int SNumberSize = 9; private static int SYearSize = 4; private static int SResultSize = 2; private static int RecordSize = (FNameSize + SNameSize + SNumberSize + SYearSize + SResultSize); private JTextField txtStudentFName = new JTextField(FNameSize); private JTextField txtStudentSName = new JTextField(SNameSize); private JTextField txtStudentNumber = new JTextField(SNumberSize); private JTextField txtStudentYear = new JTextField(SYearSize); private JTextField txtStudentResult = new JTextField(SResultSize); public static void main(String args[]) { IS2216 IS2216 = new IS2216(); } private JButton btnEnter = new JButton("Enter Result"); private JButton btnNext = new JButton("Next>"); private JButton btnBack = new JButton("<Back"); private JButton btnAttendance = new JButton("Attendance"); private RandomAccessFile raf; private String FixedLengthStringIO; public IS2216() { super("IS2216"); try { raf = new RandomAccessFile("Student.dat", "rw"); } catch(IOException ioException) { System.err.println("File does not exist"); } JPanel p1 = new JPanel(); p1.setLayout(new GridLayout(3, 1)); p1.add(new JLabel("First Name:")); p1.add(new JLabel("Surname:")); p1.add(new JLabel("Student Number:")); JPanel jpYear = new JPanel(); jpYear.setLayout(new BorderLayout()); jpYear.add(new JLabel("Year:"),BorderLayout.WEST); jpYear.add(txtStudentYear,BorderLayout.CENTER); JPanel jpResult = new JPanel(); jpResult.setLayout(new BorderLayout()); jpResult.add(new JLabel("Result:"),BorderLayout.WEST); jpResult.add(txtStudentResult,BorderLayout.CENTER); JPanel p2 = new JPanel(); p2.setLayout(new BorderLayout()); p2.add(jpYear,BorderLayout.WEST); p2.add(jpResult,BorderLayout.CENTER); JPanel p3 = new JPanel(); p3.setLayout(new BorderLayout()); p3.add(txtStudentNumber,BorderLayout.CENTER); p3.add(p2,BorderLayout.EAST); JPanel p4 = new JPanel(); p4.setLayout(new GridLayout(3, 1)); p4.add(txtStudentFName); p4.add(txtStudentSName); p4.add(p3); JPanel jpIS2216 = new JPanel(new BorderLayout()); jpIS2216.add(p1,BorderLayout.WEST); jpIS2216.add(p4,BorderLayout.CENTER); jpIS2216.setBorder(new BevelBorder(BevelBorder.RAISED)); JPanel jpButton = new JPanel(); jpButton.add(btnEnter); jpButton.add(btnBack); jpButton.add(btnNext); jpButton.add(btnAttendance); add(jpIS2216,BorderLayout.CENTER); add(jpButton,BorderLayout.SOUTH); setSize(450,175); setVisible(true); setLocation(500,250); setResizable(false); addWindowListener( new WindowAdapter() { public void windowClosing( WindowEvent event) { System.exit(0); } } ); JMenuBar menu = new JMenuBar(); JMenu fileMenu = new JMenu("File"); menu.add(fileMenu); JMenuItem NewStudent = new JMenuItem("Add Student"); NewStudent.addActionListener(new ActionListener(){ public void actionPerformed(ActionEvent e) { txtStudentFName.setText(""); txtStudentSName.setText(""); txtStudentNumber.setText(""); txtStudentYear.setText(""); txtStudentResult.setText(""); } }); fileMenu.add(NewStudent); fileMenu.addSeparator(); JMenuItem MainMenu = new JMenuItem("MainMenu"); MainMenu.addActionListener(new ActionListener(){ public void actionPerformed(ActionEvent e) { setVisible(false); welcomeP welcomeP = new welcomeP(); welcomeP.setVisible(true); } }); fileMenu.add(MainMenu); fileMenu.addSeparator(); JMenuItem logout = new JMenuItem("Logout"); logout.addActionListener(new ActionListener(){ public void actionPerformed(ActionEvent e) { JOptionPane.showMessageDialog(null,"You have been successfully logged out","Logout",JOptionPane.INFORMATION_MESSAGE); setVisible(false); Login Login = new Login(); Login.setVisible(true); } }); fileMenu.add(logout); fileMenu.addSeparator(); JMenuItem exit = new JMenuItem("Exit"); exit.addActionListener(new ActionListener(){ public void actionPerformed(ActionEvent e) { System.exit(0); } }); fileMenu.add(exit); this.setJMenuBar( menu); btnEnter.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e){ writeStudent(); txtStudentFName.setText(""); txtStudentSName.setText(""); txtStudentNumber.setText(""); txtStudentYear.setText(""); txtStudentResult.setText(""); } }); btnNext.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e){ if(e.getSource()==btnNext){ try{ long currentPosition = raf.getFilePointer(); if(currentPosition < raf.length()) readStudent(currentPosition); } catch(IOException ex){ ex.printStackTrace(); } } } }); btnBack.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e){ if(e.getSource()==btnBack){ try{ long currentPosition = raf.getFilePointer(); if(currentPosition - 2 * RecordSize > 0) readStudent(currentPosition - 2 * 2 * RecordSize); else readStudent(0); } catch(IOException ex) {ex.printStackTrace(); } } } }); try{ if(raf.length()>0)readStudent(0); } catch(IOException ex){ ex.printStackTrace(); } } //write record to file public void writeStudent(){ FixedLengthStringIO IO = new FixedLengthStringIO(); try{ raf.seek(raf.length()); IO.writeFixedLengthString(txtStudentFName.getText(), 50, raf); IO.writeFixedLengthString(txtStudentSName.getText(),50, raf); IO.writeFixedLengthString(txtStudentNumber.getText(),50, raf); IO.writeFixedLengthString(txtStudentYear.getText(), 50, raf); IO.writeFixedLengthString(txtStudentResult.getText(), 50, raf); } catch(IOException ex){ ex.printStackTrace(); } } //read record at specified position public void readStudent(long position) throws IOException{ raf.seek(position); Student s = new Student(); FixedLengthStringIO IO = new FixedLengthStringIO(); IO.readFixedLengthString(50,raf); IO.readFixedLengthString(50,raf); IO.readFixedLengthString(50,raf); IO.readFixedLengthString(50,raf); IO.readFixedLengthString(50,raf); txtStudentFName.setText(s.getFirstName()); txtStudentSName.setText(s.getSurname()); txtStudentNumber.setText(Long.toString(s.getStudentNumber())); txtStudentYear.setText(s.getYear()); txtStudentResult.setText(Integer.toString(s.getResult())); } }
