6.Suppose we have a class A which has a constructor that takes a single integer. After the following statements have been executed, how many A objects will exist (not counting garbage objects) and which objects are they? Explain your answer.

A a = new A(100);

A b = new A(150);

A c = b;

b = a;

a = null;

7.Consider this code that creates some Location objects:

Location a, b, c;

a = new Location(10,20);

b = new Location(10,20);

c = b;

After this code executes, what are the values of these boolean expressions?

a==b

a.equals(b)

a==c

a.equals(c)

b==c

b.equals(c)

8.What does the following program print out. Explain why.

public class Thing

{

public int a;

public int b;

public Thing(int a, int b)

{this.a=a; this.b=b}

}

public class Test

{

public static void f(Thing x, int y)

{

x.a++;

y++;

}

public static void main(String[] args)

{

Thing x = new Thing(1,1);

int y = 1;

f(x, y);

System.out.println("x.a = " + x.a +

}

}

9.Suppose that we have classes A, B, C and D. Suppose that B is a subclass of A, that C is a subclass of B, and D is a subclass of A. Suppose that we make the following declarations.

A a1 = new A();

A a2 = new C();

D d1 = new D();

For each part below, explain what, if any, errors would be caused by the statement in that part. Be sure to consider both compile time and run time errors.

(a) A a3 = new B();

(b) B b1 = new A();

(c) B b2 = (B) a1;

(d) B b3 = (B) a2;

(e) B b4 = (B) d1;

(f) B b5 = (C)(A)new D();

10.Let A be an array of size n 2 containing integers from 1 to n1, inclusive, with exactly one number repeated.

Write a method

public static int findRepeatedNumber(int[] A)

that returns the value of the repeated number in the array A.

What is the running time of the method?