Compile the sample test.
2. Start jdb:
$ jdb -classpath . Test
3. Set breakpoint on the line with System.out.println()
> stop at Test:6
4. Run to breakpoint
> run
5. Assign int value to variable v
> set v = 1

The following message is printed :
===================
com.sun.tools.example.debug.expr.ParseException: Attempt to set value of incorrect typecom.sun.jdi.InvalidTypeException: Can't assign primitive value to object
 v = 1 = null
==============

Note that the whitespace is missing between "type" and "com.sun.jdi.InvalidTypeException"

=====================================================
public class Test {

    public static void main(String[] args){
        MyValue v = new MyValue(12,'c');
        System.out.println("v == v " + (v == v));
    }

    public static class MyValue {
        int a;
        char b;

        public MyValue(int a, char b){
            this.a = a;
            this.b = b;
        }

    }
}