NullPointerException

[randint]

For whatever reason, there is a NullPointerException in a GUI Program I made to open files:

code:

import javax.swing.*; import java.awt.event.*; import java.io.*; public class ReadWriteFile extends JFrame implements ActionListener {         public JFrame f1 = new JFrame("Open/Save");         public JFrame f2 = new JFrame("Choose file");         public JPanel p1 = new JPanel();         public JPanel p2 = new JPanel();         public JButton b1 = new JButton ("Open");         public JButton b2 = new JButton ("Save");         public JFileChooser fc = new JFileChooser();         public File f;         public int select;         public ReadWriteFile()         {                 f1.setContentPane(p1);                 f1.setSize(300, 300);                 f1.setResizable(true);                 p1.add(b1);                 p1.add(b2);                 f2.setContentPane(p2);                 f2.setSize(500, 500);                 f2.setResizable(true);                 p2.add(fc);                 b1.addActionListener(this);                 b2.addActionListener(this);                 f1.setVisible(true);         }         public void actionPerformed(ActionEvent e)         {                 if (e.getSource() == b1)                 {                         f2.setVisible(true);                         FileRead();                 }         }         public void FileRead()         {                 if (select == fc.APPROVE_OPTION)                 {                         f = fc.getSelectedFile();                 }         }         public static void main(String args[]) throws Exception         {                 ReadWriteFile rwf = new ReadWriteFile();         } }

The java.lang.NullPointerException occurs when the user attempts to open a file, I do not know why this is.[/list]

[Tony]

Because, on the line where this exception is thrown, you are trying to call a method on NULL. Try to step backwards to figure out why that variable did not have any value assigned to it.