These questions are courtesy of Whizlabs Software and will help you prepare for the Sun Certified Java Programmer Exam 5.0 (SCJP).

Question No. 1 - What is the result of compiling and running the following code?

{moscode}
import java.util.*;

class Gen {
        T obj;
        Gen(T o){
                obj=o;
        }

        T get() {
                return obj;
        }
}

class Generics19{
        public static void main(String[] args){
                Gen i1=new Gen(new Integer(10));
                int i=i1.get();
                System.out.println(i);
        }
}

A.Compiler error
B.Exception
C.Prints 10
D.Prints 0
{/moscode}

Question No. 2 - Select the most appropriate implementation of the hashCode() method that can be inserted at line 15 in the following code. Assume that the equals() method is implemented correctly in this class.

1.      public class TestHash
2.      {
3.              private int length;
4.              private int width;
5.              private final double area;
6.              
7.              // only one constructor
8.              public TestHash(int l, int w)
9.              {
10.                     length = l;
11.                     width = w;
12.                     area = length * width;
13.             }
14.             
15.             // what should be inserted here?
16.             
17.             // equals method not shown
18.     }

A. public int hashCode()
{
        int hash = 7;
        hash = 31 * hash + length;
        hash = 31 * hash + width;
        long bits = Double.doubleToLongBits(area);
        return hash;
}

B. public int hashCode()
{
        int hash = 7;
        hash = 31 * hash + length;
        hash = 31 * hash + width;
        long bits = Double.doubleToLongBits(area);
        hash = 31 * hash + (int)(bits  (bits >>> 32)); 
        return hash;
}

C. public int hashCode()
{
        int hash = 7;
        hash = 31 * hash + length;
        hash = 31 * hash + width;
        return hash;
}

D. public long hashCode()
{
           int hash = 7;
           hash = 31 * hash + length;
           return hash;
}