Inheritance Unit Test

What is the output by the code below?

public class J

{

private int x, y;

public J() {

x = y = 3;

}

public void fun() {

x = y = 6;

}

public int back() {

return 1;

}

public String toString() {

return x + " " + y;

}

}

public class K extends J {

public void fun() {

out.println(back());

}

public String toString() {

return "class K " + super.toString();

}

}

//test code in a client program

J runner = new K();

out.println(runner);

Which of the following lines would correctly fill /* blank */ to pass x to the appropriate parent constructor?

public class P

{

private int one;

public P(){ one=0; }

public P(int num){

one=num;

}

}

public class Q extends P

{

public Q() { }

public Q(int x){

/* blank */

}

}

What is output by the code below?

Object c = new String("Hello");

String d = new String("Hello");

System.out.println(c.equals(d));

What is the output of line 2?

public class X{

public void one(){

System.out.print("Xone");

}

public void two(){

System.out.print("Xtwo");

}

}

public class Y extends X{

public void one(){

System.out.print("Yone");

}

public void two(){

System.out.print("Ytwo");

}

public void testIt(){

one();

super.one();

two();

super.two();

}

}

//code in the main of another class

Y code = new Y();

code.one(); //line 1

code.testIt(); //line 2

What is output by the code below?

public class Cat {

private int x, y;

public Cat() {

x=y=5;

}

public void fun() {

x=7;

}

public double go() {

return x;

}

public void back() {

fun();

}

public String toString() {

return x + " " + y;

}

}

public class Lion extends Cat {

private int x;

public Lion() {

x=9;

}

public void fun() {

x=3;

}

public double go() {

return x;

}

public void back() {

super.back();

}

public String toString() {

return super.toString() + " " + x;

}

}

//code in a client program

Cat fred = new Lion();

fred.fun();

System.out.println(fred.go());

What is output by the code below?

public class Whale

{

private int x, y;

public static int c;

public Whale() {

c++;

}

public void fun() {

x = 6;

}

public int back() {

return 1;

}

public String toString() {

return x + " " + y + " " + c;

}

}

public class Beluga extends Whale

{

public void fun() {

System.out.println(back());

}

public int back() {

return 2;

}

public String toString() {

return "class Beluga " + super.toString();

}

}

//code in the main of another class

Whale flipper = new Beluga();

flipper = new Whale();

flipper = new Beluga();

flipper = new Whale();

flipper.fun();

System.out.println(flipper);

Consider the following code.

public interface Box

{

int mystery(int num);

}

public abstract class Stuff

{

private int x;

public Stuff()

{

x = 5;

}

public Stuff(int newX)

{

x = newX;

}

public abstract void doStuff();

public abstract int doubleIt();

}

public class LotsOfStuff extends Stuff implements Box

{

/* implementation not shown */

}

What methods should the class LotsOfStuff implement?

Which methods must be implemented in any class that inherits from the class Stuff?

public abstract class Stuff

{

private int x;

public Stuff()

{

x = 5;

}

public Stuff(int newX)

{

x = newX;

}

public abstract void doStuff();

public abstract int doubleIt();

}

What is the number of methods a class extending abstract class Aplus should implement?

public abstract class Aplus

{

public Aplus()

{

}

public abstract String destroy();

public String toString()

{

return "--";

}

}

public class X __________________ Y _____________________ A, B, C

All variables located inside of an interface are automatically set with what access?

Which of the following is the correct way to write the interface Screen?

I.

public interface Screen

{

void updateDisplay()

{

}

int getTime();

}

II.

public interface Screen

{

public Screen()

{

}

void updateDisplay();

int getTime();

}

III.

public interface Screen

{

void updateDisplay();

int getTime();

}

Directions :: Extend class Drink to make a Tea class. Tea must have a constructor. Tea must have an instance variable for type of tea. Tea must have an instance variable for the amount left. Tea must have a Boolean method that determines if the Tea is empty. Tea must have a method that removes 1 from amount left when a drink is taken.