Test : Java_4

This test contains 10 questions based on Java.
Each question answered correctly awards you 1 point and each incorrect answer has a penalty of -0.25 points, no points are deducted for unattempted answers.

Select Test Type

You Get +1 for each correct answer and -0.25 for each incorrect answer

Time Left - minutes :seconds

1. Class A  
2.    {  
3.     public static void main(String a1[])  
4.     {  
5.       String s1= ?Hello?;  
6.       StringBuffer s2= new StringBuffer(?Hello?);  
7.       s1 = s1 + ?World?;  
8.       s2.append(?World?);  
9.     }  
10.    }  

In the above code how many String and StringBuffer objects are created?

1 & 1	2 & 1
2 & 2	1 & 2

B

Difference between String and StringBuffer object is immutable and mutable respectively. Code s1+ ?World? will create a new String object ?HelloWorld? with new reference is assigned to s1 and looses ?Hello? String object reference. So two String object is created from the above code.In the case of StringBuffer s2.append(?World?) will modify the existing object s2 and creates only one object because it is mutable.

What is the output of this program?

 class exception_handling {
        public static void main(String args[]) {
            try {
                int a, b;
                b = 0;
                a = 5 / b;
                System.out.print("A");
            }
            catch(ArithmeticException e) {
         System.out.print("B");         
            }
            finally {
             System.out.print("C");
            }
        }
    }

A	B
AC	BC

D

Which of these method wakes up the first thread that called wait()?

wake()	notify()
start()	notifyAll()

B

Which of the following statements is correct?

Public method can be accessed by calling object of the public class.	Public method is accessible only to subclasses of its parent class
Public method can only be called by object of its class.	Public method is accessible to all other classes in the hierarchy

D

Which of these keywords is not a part of exception handling?

try	finally
thrown	catch

C

Which of these is used to access member of class before object of that class is created?

public	private
static	protected

C

Which of the following statements are true? (A) An abstract class may not have any final methods. (B) A final class may not have any abstract methods. (C) An inner class may be declared with any accessibility keyword. (D) Transient variables must be static.

B) & (C)	(A)
(A) & (C)	(D)

A

Which of these keywords are used to define an abstract class?

abst	abstract
Abstract	abstract class

B

Which of the following are the wrapper classes? (A) Random (B) Byte (C) Vector (D) Integer (E) Short (F) Double (G) String

(B), (D) & (F)	(A), (B), (D), (E) & (F)
(B), (D), (E) & (F)	(D), (E) & (F)

C

Which of the following is correct way of implementing an interface salary by class manager?

class manager extends salary {}	class manager implements salary {}
class manager imports salary {}	None of the mentioned

B

Finish Test