Null pointer Exception

[Mikael Fox]

Hello,
I am having a null pointer error, don't know where it came out. Can someone check this code for me please:

The error is in the sendBytes methods, I have put a comment over there, actually there are two null errors. Line 57 and 64.

1.

 pw.println(filenm);

2.

out.write(buffer,0,bytes);

Thanks a lot in advance.




This is the code:

import java.net.*;
import java.io.*;
import javax.swing.JOptionPane;


public class FTPClient implements Runnable {


Socket s;
long length;
File file;

	InputStreamReader in = null;
	OutputStream out = null;
	BufferedReader br = null;
	PrintWriter pw = null;

    String filenm  = null;
    String fn;

public FTPClient(){

}

public FTPClient(int port){
    connectToServer(port);
    new Thread( this ).start();
}

//connect to the server
public void connectToServer(int port){

   try{    
                s  = new Socket ("127.0.0.1" , port);
                br = new BufferedReader(new InputStreamReader(s.getInputStream()));
                pw = new PrintWriter(s.getOutputStream(),true);
                out = s.getOutputStream();

                JOptionPane.showMessageDialog(null, "Client says: ... I am connected and IO Ready!");

        }catch(Exception e){e.printStackTrace();}
}




//send bytes to server
public void sendBytes(File f){
     
        try{

            JOptionPane.showMessageDialog(null, "Client says: File send ....");
            JOptionPane.showMessageDialog(null, "Client says: The file name: " + f.getName());
            JOptionPane.showMessageDialog(null, "Client says: The file size: " + f.length());

            filenm = f.getName();
            pw.println(filenm);  // got a java.lang.NullPointerException here 
            FileInputStream fis = new FileInputStream(filenm);
            byte[] buffer=new byte[1024];
            int bytes=0;

            while((bytes=fis.read(buffer))!=-1)
            {
                out.write(buffer,0,bytes); // got a java.lang.NullPointerException here also when I comment //  pw.println(filenm);  the first one
                JOptionPane.showMessageDialog(null, "Test .... ");
            }

            fis.close();

        }catch(Exception e){e.printStackTrace();}

}



}

This is the error:

run-single:
java.lang.NullPointerException
at ignisftpv3.FTPClient.sendBytes(FTPClient.java:85)
at ignisftpv3.FTPClientInterface.btnSendActionPerformed(FTPClientInterface.java:121)
at ignisftpv3.FTPClientInterface.access$100(FTPClientInterface.java:8)
at ignisftpv3.FTPClientInterface$2.actionPerformed(FTPClientInterface.java:48)
at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:1995)
at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2318)
at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:387)
at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:242)
at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:236)
at java.awt.Component.processMouseEvent(Component.java:6038)
at javax.swing.JComponent.processMouseEvent(JComponent.java:3260)
at java.awt.Component.processEvent(Component.java:5803)
at java.awt.Container.processEvent(Container.java:2058)
at java.awt.Component.dispatchEventImpl(Component.java:4410)
at java.awt.Container.dispatchEventImpl(Container.java:2116)
at java.awt.Component.dispatchEvent(Component.java:4240)
at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4322)
at java.awt.LightweightDispatcher.processMouseEvent(Container.java:3986)
at java.awt.LightweightDispatcher.dispatchEvent(Container.java:3916)
at java.awt.Container.dispatchEventImpl(Container.java:2102)
at java.awt.Window.dispatchEventImpl(Window.java:2429)
at java.awt.Component.dispatchEvent(Component.java:4240)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:599)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:273)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:183)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:173)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:168)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:160)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:121)
BUILD SUCCESSFUL (total time: 3 minutes 10 seconds)

[Paul Clapham]

The pw and out variables are null because you never assign them a value. Sure, you have some code which would assign them values if it were executed, but it wasn't executed. (You can tell that because pw and out are null.)

If you look at your stderr output, you should be able to see why that code wasn't executed.