Question

In servlet side, I am trying to receive an vector sent from the applet. The code is like

InputStream in = request.getInputStream();
ObjectInputStream inputFromApplet = new ObjectInputStream(in);
Vector v = (Vector) inputFromApplet.readObject();

But the compiler specifies that the following one is wrong.

Vector v = (Vector) inputFromApplet.readObject();

The error message is

Multiple markers at this line

• Unhandled exception type ClassNotFoundException
• Vector is a raw type. References to generic type Vector
  should be parameterized
• Vector is a raw type. References to generic type Vector
  should be parameterized

What’s wrong with my code? Thanks.

Answer 1

For the exception, wrap your code in

try {
   <your code here>
} catch (ClassNotFoundException e) {
   <code that happens when class can't be found>
}

The other messages are warnings which won’t stop your program from compiling. They refer to needing a parameter on parametrised types to adhere to new specifications (as of Java 1.5). So, if you want to store integers in a Vector, use Vector<Integer>. This changes the methods to requiring Integers instead of the generic Object you’d normally get and increases type-safeness.