Q:

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerExceptionn

I want to open a file in jTextPane in read mode. But its giving some exception...
What should I do? 
Should I need to write ActionListner?
I am new to java .. So help me out Friends..
My code is given below..
try {
        // TODO add your handling code here:
        BufferedReader input=null;
        File file=new JFileChooser().getSelectedFile();
        /* Line no 524 */input = new BufferedReader(new InputStreamReader(new  FileInputStream(file)));
        jTextPane1.read(input, "READING FILE :-)");
    } catch (IOException ex) {
        Logger.getLogger(ExcelSheet.class.getName()).log(Level.SEVERE, null, ex);
    }

And these are the exceptions
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at java.io.FileInputStream.<init>(FileInputStream.java:103)
at cvparser.ExcelSheet.jButton2ActionPerformed(ExcelSheet.java:524)
at cvparser.ExcelSheet.access$300(ExcelSheet.java:36)
at cvparser.ExcelSheet$4.actionPerformed(ExcelSheet.java:207)
at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:1995)
at javax.swing.AbstractButton$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:6263)
at javax.swing.JComponent.processMouseEvent(JComponent.java:3267)
at java.awt.Component.processEvent(Component.java:6028)
at java.awt.Container.processEvent(Container.java:2041)
at java.awt.Component.dispatchEventImpl(Component.java:4630)
at java.awt.Container.dispatchEventImpl(Container.java:2099)
at java.awt.Component.dispatchEvent(Component.java:4460)
at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4574)
at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4238)
at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4168)
at java.awt.Container.dispatchEventImpl(Container.java:2085)
at java.awt.Window.dispatchEventImpl(Window.java:2475)
at java.awt.Component.dispatchEvent(Component.java:4460)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:599)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)

A:

Doing this File file=new JFileChooser().getSelectedFile(); is simply creating an instance of a JFileChooser and asking it to pass back what ever represents a selected file.  But seen as no file has been selected, it is return back null...
Try something more like...
JFileChooser fc = new JFileChooser();
switch (fc.showOpenDialog(null)) {
    case JFileChooser.APPROVE_OPTION:
        File file= fc.getSelectedFile();
        break;
}

Take a look at How to use file choosers for more details.
Updated with file reading example
JFileChooser fc = new JFileChooser();
switch (fc.showOpenDialog(null)) {
    case JFileChooser.APPROVE_OPTION:
        File file= fc.getSelectedFile();
        BufferedReader br = null;
        try {
            input = new BufferedReader(new FileReader(file));
            jTextPane1.read(input, "READING FILE :-)");
        } catch (IOException exp) {
            exp.printStackTrace();
        } finally {
            try {
                br.close();
            } catch (Exception exp) {
            }
        }
        break;
}

