compiler error:"AWT-EventQueue-0" java.lang.NullPointerException at java.io.Reader.

[Ms.Ranjan]

Hi

I am stuck up with this error

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
        at java.io.Reader.<init>(Unknown Source)
        at java.io.InputStreamReader.<init>(Unknown Source)
        at View.read(View.java:146)
        at Assigning.assattr(Assigning.java:18)
        at Execute.actionPerformed(Execute.java:73)
        at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)
        at javax.swing.AbstractButton$Handler.actionPerformed(Unknown Source)
        at javax.swing.DefaultButtonModel.fireActionPerformed(Unknown Source)
        at javax.swing.DefaultButtonModel.setPressed(Unknown Source)
        at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(Unknown Sour
ce)
        at java.awt.Component.processMouseEvent(Unknown Source)
        at javax.swing.JComponent.processMouseEvent(Unknown Source)
        at java.awt.Component.processEvent(Unknown Source)
        at java.awt.Container.processEvent(Unknown Source)
        at java.awt.Component.dispatchEventImpl(Unknown Source)
        at java.awt.Container.dispatchEventImpl(Unknown Source)
        at java.awt.Component.dispatchEvent(Unknown Source)
        at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source)
        at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source)
        at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)
        at java.awt.Container.dispatchEventImpl(Unknown Source)
        at java.awt.Window.dispatchEventImpl(Unknown Source)
        at java.awt.Component.dispatchEvent(Unknown Source)
        at java.awt.EventQueue.dispatchEvent(Unknown Source)
        at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
        at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
        at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
        at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
        at java.awt.EventDispatchThread.run(Unknown Source)

Here is the code snippet which is causing this error

public class View
{
     public InputStreamReader read(String name)
    {
         ClassLoader loader = Viewplugin.class.getClassLoader();		
 	InputStream is=loader.getResourceAsStream("source/"+name);
[B] InputStreamReader isr=new InputStreamReader(is);  //View.read(View.java:146)[/B]
 		return isr;
    }
}

public class Assigning
{
  View vi=new View();
  public String assattr(String filename,String nodestring)
	{
		String st1;		
		[B]InputStreamReader attrfile=vi.read(filename);  //Assigning.assattr(Assigning.java:18)[/B]
	     BufferedReader buff=new BufferedReader(attrfile);
	     try {
	 		//code here
	 	   } catch (IOException e) {
	 		// TODO Auto-generated catch block
	 		e.printStackTrace();
	 	  }	 
		
	 return somestring;
	}
}  
}

public class Execute implements ActionListener {
public void actionPerformed(ActionEvent e)
	    {
          Assigning aa=new Assigning();
          for(String s:list)
          {
              if(s.equals("one"))
              {
               String at1=aa.assattr("attr1.noa",s);
              }
              else if(s.equals("two"))
              {
                [B]String at2=aa.assattr("attr2.noa",s); //Execute.actionPerformed(Execute.java:73)[/B]
              }
              else
              {
                 System.out.println("Not assigned");
               }
          }
}
}

can someone plz explain me what is causing this error??
String at1=aa.assattr("attr1.noa",s);//this assignment works perfectly fine
String at2=aa.assattr("attr2.noa",s); this is the line where it showing the error i am just changing the filename,the files are available they donot have any null values,i am not sure where i am gng wrong,if someone could point it out,it would be of great help

Thanks

[hardwired]

Try closing the BufferedReader before leaving the View assattr method:

    ...
    BufferedReader buff=new BufferedReader(attrfile);
    try {
        //code here
        buff.close();
    } catch (IOException e) {
        e.printStackTrace();
    }
    return somestring;
}

Do some debugging in the View read method:

    ...
    System.out.println("is = " + loader.getResourceAsStream("source/"+name));
    InputStream is=loader.getResourceAsStream("source/"+name);
    InputStreamReader isr=new InputStreamReader(is);
    System.out.println("isr = " + isr);
    return isr;
}

[Ms.Ranjan]

I tried with buff.close() but i get the same error..anyother suggestion plz

[Ms.Ranjan]

Thanks guys..its solved..

[itoldi]

Hi Ms.Ranjan, could you please tell me how you had solved the problem above? I am stuck up with the eroor faolowing
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at java.io.Reader.<init>(Unknown Source)
at java.io.InputStreamReader.<init>(Unknown Source)
at java.util.Scanner.<init>(Unknown Source)
at ResourceTestFrame.<init>(ApletTest.java:37)
at ApletTest$1.run(ApletTest.java:17)
at java.awt.event.InvocationEvent.dispatch(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForFilter s(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForFilter(U nknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarch y(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)

the code snippet causing this error is:
JTextArea textArea = new JTextArea();
InputStream stream = getClass().getResourceAsStream("about.txt");
Scanner in = new Scanner(stream); //(ApletTest.java:17)