We have an application which requires us to read data from a file (.dat) dynamically using deserialization. We are actually getting first object and it throws null pointer exception when we are accessing other objects using a "for" loop.

            File file=null;
             FileOutputStream fos=null;
             BufferedOutputStream bos=null;
             ObjectOutputStream oos=null;
             try{
                 file=new File("account4.dat");
                 fos=new FileOutputStream(file,true);
                 bos=new BufferedOutputStream(fos);
                 oos=new ObjectOutputStream(bos);
                 oos.writeObject(m);
                 System.out.println("object serialized");
                 amlist=new MemberAccountList();
                 oos.close();
             }
           catch(Exception ex){
             ex.printStackTrace();
           }

Reading objects:

try{ MemberAccount m1; file=new File("account4.dat");//add your code here fis=new FileInputStream(file); bis=new BufferedInputStream(fis); ois=new ObjectInputStream(bis); System.out.println(ois.readObject()); while(ois.readObject()!=null){ m1=(MemberAccount)ois.readObject(); System.out.println(m1.toString()); }/mList.addElement(m1); // Here we have the issue throwing null pointer exception Enumeration elist=mList.elements(); while(elist.hasMoreElements()){ obj=elist.nextElement(); System.out.println(obj.toString()); }/

} catch(ClassNotFoundException e){

    }
    catch(EOFException e){
        System.out.println("end");
    }
    catch(Exception ex){
        ex.printStackTrace();
    }