RMI: FileNotFound exception and NullPointException

[Yohan Weerasinghe]

Hi,

Please have a look at the following set of codes

FileChoose.java

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.io.*;
import java.rmi.Naming;

public class FileChoose extends JFrame
{
    private JButton choose;
    private JPanel southPanel, centerPanel, northPanel, scrollPanel;
    private FlowLayout flow1, flow2,flow3;
    private JFileChooser fileChooser;
    private int returnValue;
    private JLabel text;
    private JTextArea area;
    private JScrollPane scroll;
    private File folder, listOfFiles[], file, outputFile;
    FileChooseRemote f;
    byte[] data;
    
    public FileChoose()
    {
        choose = new JButton("Choose");
        choose.addActionListener(new Button());
        text = new JLabel("File selected");
        area = new JTextArea(10,50);
        fileChooser = new JFileChooser("C:/javay");
        scroll = new JScrollPane(area);
        scroll.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED);
        scroll.setHorizontalScrollBarPolicy(JScrollPane.HORIZONTAL_SCROLLBAR_NEVER);
        area.setLineWrap(true);
        
        flow1 = new FlowLayout(FlowLayout.CENTER);
        flow2 = new FlowLayout(FlowLayout.CENTER);
        flow3 = new FlowLayout(FlowLayout.CENTER);
        
        scrollPanel = new JPanel();
        scrollPanel.add(scroll);
        
        northPanel = new JPanel();
        northPanel.setLayout(flow1);
        northPanel.add(choose);
        
        centerPanel = new JPanel();
        centerPanel.setLayout(flow3);
        centerPanel.add(scrollPanel);
        
        southPanel= new JPanel();
        southPanel.setLayout(flow2);
        southPanel.add(text);
        
        folder = new File("C:/javay/rmi/copy2/server");
        listOfFiles = folder.listFiles();
        
        for(int i=0;i<listOfFiles.length;i++)
        {
            String listString = listOfFiles[i].getName().toString();
            area.append(listString+"\n");
        }
        
        
        getContentPane().add(northPanel,"North");
        getContentPane().add(southPanel,"South");
        getContentPane().add(centerPanel,"Center");
        
        
        
    }
    
    private class Button implements ActionListener
            
    {
        public void actionPerformed(ActionEvent ae)
        {
            if(ae.getSource().equals(choose))
            {
                returnValue = fileChooser.showOpenDialog(FileChoose.this);
                
                if(returnValue == JFileChooser.APPROVE_OPTION)
                {
                     file = fileChooser.getSelectedFile();
                    
                    try
                    {
                         f = (FileChooseRemote)Naming.lookup("rmi://localhost/FServer");
                         sendFile();
                         createFile();
                    }
                    catch(Exception e)
                    {
                        JOptionPane.showMessageDialog(null,"Error in LkkoUp: "+e.getMessage());
                    }
                }
            }
        }
    }
    
    private void sendFile()
    {
        try
        {
            data = f.loadFile(file.getName());
        }
        catch(Exception e)
        {
            JOptionPane.showMessageDialog(null,"Error sending the file: "+e);
        }
    }
    
    private void createFile()
    {
        try
        {
            outputFile = new File(file.getName());
            BufferedOutputStream out = new BufferedOutputStream(new FileOutputStream(outputFile.getName()));
            out.write(data, 0, data.length);
            out.flush();
            out.close();
            text.setText("File Downloaded");
        }
        catch(Exception e)
        {
            JOptionPane.showMessageDialog(centerPanel, "Error in downloading: "+e);
            e.printStackTrace();
        }
        
        
    }
    
    public static void main(String[]args)
    {
        try
        {
            UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
        }
        catch(Exception e)
        {
            JOptionPane.showMessageDialog(null, "GUI Error: "+e);
        }
        
        FileChoose f = new FileChoose();
        f.setVisible(true);
        f.setSize(500,500);
        f.validate();
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }
    
}

FileChooseRemote.java

import java.rmi.*;

public interface FileChooseRemote extends Remote
{
    public byte[] loadFile(String fileName)throws RemoteException;
}

FileChooseRemoteImpl.java

import java.rmi.*;
import java.io.*;
import java.rmi.server.*;

public class FileChooseRemoteImpl extends UnicastRemoteObject implements FileChooseRemote
{
    private File file;
    private byte[] buffer;
    BufferedInputStream input;
    
    public FileChooseRemoteImpl() throws RemoteException
    {
        super();
    }
    
     public byte[] loadFile(String fileName)throws RemoteException
     {
         try
         {
            file = new File(fileName);
         
             buffer = new byte[(int)file.length()];
         
             input = new BufferedInputStream(new FileInputStream(fileName));
             
             input.read(buffer, 0, buffer.length);
             
             input.close();
             
             return (buffer);
         }
         catch(Exception e)
         {
             e.printStackTrace();
         }
         return (null);
         
         
     }
}

FileChooseServer.java

import java.rmi.*;

public class FileChooseServer
{
    public static void main(String[]args)
    {
        System.setSecurityManager(new RMISecurityManager());
        
        try
        {
            FileChooseRemote f = new FileChooseRemoteImpl();
            Naming.rebind("FServer", f);
            
            System.out.println("Object Registered");
            System.out.println("Wainting for a request");
        }
        catch(Exception e)
        {
            e.printStackTrace();
        }
    }
}

In here, when I click the button, it and selected the required file, the FileChooser.java is generating the exception "NullPointException" and FileChooseServer.java generates an exception "java.io.fileNotFound". I can't find the solution. Please help. Thanks>

[Edward Harned]

Limit your code

[Yohan Weerasinghe]

Managed to solve the issue by my self. The error was, we have to select a file from the server folder, not from anywhere else. My JFileChooser was adjust to another location, I recorrected it by adjusting it to the server folder.