Question 1

Here is a situation: Birthday happy; happy = new AdultBirthday( "Joe", 39); happy.greeting(); Which greeting() method is run: the one defined for Birthday or the one defined for AdultBirthday?

Accepted Answer

The one defined for AdultBirthday because that is the type of the object referred to by happy.

Question 2

Which among the following can't be used for polymorphism?
Group of answer choices

Predefined operator overloading

Member functions overloading

Static member functions

Constructor overloading

Accepted Answer

Static member functions

Question 3

Casting superclass references to subclass references is known as downcasting.

Accepted Answer

True

Question 4

Which among the following is not true for polymorphism?

Accepted Answer

Increases overhead of function definition always

Question 5

What must be true if a child of an abstract parent class does not override all of the parent's abstract methods?

Accepted Answer

The child class itself must be declared to be abstract.

Question 6

Which of the following is FALSE about abstract classes in Java

Accepted Answer

A class can inherit from multiple abstract classes.

Question 7

Which is the following statement(s) is/are correct?
X: A class can be marked as abstract with out containing any abstract method.

Y: If a class has even one abstract method, then the class has to be an abstract class.

Accepted Answer

Both are correct

Question 8

Which is true about interfaces in java
1) interface can have  type of member public, static, final fields default  static methods w/ bodies
2) instance of interface can be created
3) class can implement multiple interfaces.
4) Many classes can impleme

Accepted Answer

1, 3 and 4

Question 9

Which of the following statement(s) is/are correct?

X: An abstract class can have one or more abstract methods.

Y: An abstract class can have only abstract. Non abstract (or concrete) methods are not allowed.

Accepted Answer

X only

Question 10

What is an abstract method?

Accepted Answer

An abstract method is one without a body that is declared with the reserved word abstract.

Question 11

Which among the following is not a method of Throwable class?
Group of answer choices

public void printStackTrace()

public String getMessage()

public Char toString()

public Throwable getCause()

Accepted Answer

public Char toString()

Question 12

Why do we need to handle exceptions?
Group of answer choices

To encourage exception prone program

To avoid syntax errors

To save memory

To prevent abnormal termination of program

Accepted Answer

To prevent abnormal termination of program

Question 13

What are two exception classes in hierarchy of java exceptions class?
Group of answer choices

Runtime exceptions only

Other exceptions

Runtime exceptions and other exceptions

Compile time exceptions only

Accepted Answer

Runtime exceptions and other exceptions

Question 14

public class Test extends Exception{   
     private String mess; 
 public Test(String message)
          this.mess = mess;
     public static void main(String[] args)
          int a = 5, b = 3;
          try 
 if( a % b > 0 )
 throw new test

Accepted Answer

Compilation error

Question 15

What happens during execution if an negative value is used for an array index?

Accepted Answer

An IndexOutOfBoundsException is thrown.

Question 16

Only way to enable assertion for your program is by using command line arguments.

Accepted Answer

False

Question 17

What happen when you compile  with command “java Test -10”
public class Test{
public static void main(String[] args){
int temp = Integer.parseInt(args[0]);            
assert temp > 0 : temp = 0; 
System.out.println(temp);

Accepted Answer

The code will not compile

Question 18

which line is an example of an inappropriate use of assertions?
        assert z > 0; /* Line 11 */
        assert z > 2: foo(z); /* Line 12 */
            assert z > 4; /* Line 14 */
            assert z > 4: z++; /* Line 22 */

Accepted Answer

Line 22

Question 19

Which of the following statements is true?

Accepted Answer

It is sometimes good practice to throw an AssertionError explicitly.

Question 20

What will happen when you compile w/ assertion 
public class Test{
public static void main(String[] args){
displayAge(20);
}
private static void displayAge(int age){
assert age >= 21 : getAgeMessage();
System.out.println(age);
}
private static St

Accepted Answer

The code will compile but will throw AssertionError when executed

Question 21

Fill in the blanks so that the following draws a Frame containing "Hello".
import java.awt.*;
class helloFrame ___________ Frame{
public void ___________( Graphics g ){
g.___________("Hello", 10, 50 );}}

Accepted Answer

extends, paint, drawString

Question 22

An abstract class declares a common interface for the various members of a class hierarchy. The abstract class contains methods that will be declared in the subclasses. All classes in the hierarchy can use this same set of methods through polymorphism.

Accepted Answer

True

Question 23

Unfortunately, polymorphic programs make it difficult to add new capabilities to a system.

Accepted Answer

False

Question 24

What do you call the languages that support classes but not polymorphism?
Group of answer choices

If classes are supported, polymorphism will always be supported

Object-based language

Procedure Oriented language

Class based language

Accepted Answer

Object-based language

Question 25

Rodent rod;
Rat rat = new Rat();
Mouse mos = new Mouse();
PocketMouse pkt = new PocketMouse();
Which one of the following will cause a compiler error?

Accepted Answer

pkt = rat;

Question 26

Which of the following classes fail to compile?

class X { }

abstract class Y { }

class Z { abstract void method(); }

Accepted Answer

Z

Question 27

Abstraction principle includes___________
Group of answer choices

Use abstraction whenever possible to avoid duplication

Use abstraction to avoid longer codes

Use abstraction whenever possible to achieve OOP

Use abstraction at its minimum

Accepted Answer

Use abstraction whenever possible to avoid duplication

Question 28

Can an abstract method be defined in a non-abstract class?

Accepted Answer

No--if a class defines an abstract method the class itself must be abstract.

Question 29

Higher the level of abstraction, higher are the details.

Accepted Answer

False

Question 30

Why do we use finally block?
Group of answer choices

To execute a code when exception is not occurred

To execute a code whenever required

To execute a code with each and every run of program

To execute the block if exception occurred

Accepted Answer

To execute a code whenever required

Question 31

An exception may arise when _______________
Group of answer choices

Input is valid

Input is fixed

Input is some constant value of program

Input given is invalid

Accepted Answer

Input given is invalid

Question 32

Say that a method catches an IOException in a catch{} block. Is it possible for that block to do some processing and then throw the same exception to the caller?

Accepted Answer

Yes---as long as the method also has a throws clause for that exception.

Question 33

There can be a try block without catch block but vice versa is not possible.
Group of answer choices

False

True

Accepted Answer

True

Question 34

It is not required for the caller method to catch or re-throw the checked exception.

Accepted Answer

False

Question 35

assert false; /* Line 5 */
assert false; /* Line 6 */
  while(true)
        {
 assert false; /* Line 12 */
  } 
 assert false;  /* Line 14 */

Accepted Answer

Line 14, kase infinite loop yung line 12

Question 36

What will be the output of the program (when you run with the -ea option) ?
public class Test
{ 
 public static void main(String[] args)
 {
 int x = 0; 
 assert (x > 0) : "assertion failed"; /* Line 6 */
System.out.println("finished");

Accepted Answer

An AssertionError is thrown.

Question 37

What causes compilation to fail?
 assert false; /* Line 5 */
assert false; /* Line 6 */
  while(true)
        {
 assert false; /* Line 12 */
  } 
 assert false;  /* Line 14 */

Choices:
Line12

Line13

Line 10

Line 14

Accepted Answer

Line 14

Question 38

public class Test{
public static void main(String[] args){
int[] marks = {40, 38, 52};
boolean[] pass = {false, false, false};
for(int i = 0 ; i < marks.length; i++){
try{
assert marks[i] >= 40 : pass[i] = true;
}catch(AssertionError ae){
pass[i]

Accepted Answer

The code will compile and print false,false,false,

"Know" box contains:
Time elapsed:
Retries:

OOP fa4