Java sample(File IO)

//Example14
import java.io.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.filechooser.*;
public class Example14{
  JTextField tf01=new JTextField("",20);
  JTextField tf02=new JTextField("",20);
  //main
  public static void main(String ar[]){
    Example14 sample=new Example14();
  }
  //constructor
  Example14(){
    JFrame f=new JFrame("File IO");
    f.setDefaultCloseOperation(f.EXIT_ON_CLOSE);
    JButton bt01=new JButton("Open");
    bt01.setActionCommand("Open");
    bt01.addActionListener(new PushButtonActionListener(f));
    JButton bt02=new JButton("Save");
    bt02.setActionCommand("Save");
    bt02.addActionListener(new PushButtonActionListener(f));
    JPanel p1=new JPanel();
    p1.add(bt01);
    p1.add(bt02);
    f.getContentPane().add(p1,BorderLayout.NORTH);
    JPanel p2=new JPanel();
    p2.add(tf01);
    p2.add(tf02);
    f.getContentPane().add(p2,BorderLayout.CENTER);
    f.setSize(640,400);
    f.setVisible(true);
  }
  //action listener
  private class PushButtonActionListener implements ActionListener{
    JFrame f = null;
    public PushButtonActionListener(JFrame af) {
      this.f = af;
    }
    public void actionPerformed(ActionEvent ae){
      if(ae.getActionCommand()=="Open"){
        tf01.setText("");
        tf02.setText("");
        JFileChooser fc=new JFileChooser(System.getProperty("user.dir"));
        int fd=fc.showOpenDialog(f);
        try{
          if(fd==JFileChooser.APPROVE_OPTION){
            FileInputStream fi=new FileInputStream(fc.getSelectedFile());
            BufferedReader br=new BufferedReader(new InputStreamReader(fi));
            String s01=br.readLine();
            if(s01 != null) tf01.setText(s01);
            String s02=br.readLine();
            if(s02 != null) tf02.setText(s02);
            br.close();
            fi.close();
          }
        }
        catch(Exception ex){}
      }else if(ae.getActionCommand()=="Save"){
        JFileChooser fc=new JFileChooser(System.getProperty("user.dir"));
        int fd=fc.showSaveDialog(f);
        try{
          if(fd==JFileChooser.APPROVE_OPTION){
            FileOutputStream fo=new FileOutputStream(fc.getSelectedFile());
            PrintStream ps=new PrintStream(fo);
            ps.println(tf01.getText());
            ps.println(tf02.getText());
            ps.close();
            fo.close();
          }
        }
        catch(Exception ex){}
      }
    }
  }
}