Ubinetics Placement Paper -: Java Questions And Answers

Ubinetics Previous Years Solved Sample Placement Papers

1. What is the output of the following program?

       public class Question {
       public static void main(String args[]) {
           String s1 = "abc";
           String s2 = "def";
           String s3 = s1.concat(s2.toUpperCase());
           System.out.println(s1 + s2 + s3);
       }
       }
       

   a) abcdefabcdef b) abcabcDEFDEF c) abcdefabcDEF d) None of the above Answer: c) abcdefabcDEF Explanation: The string s3 is formed by concatenating s1 and the uppercase of s2, resulting in "abc" + "def" + "DEF", so the output is "abcdefabcDEF".

2. Which one of the following is not an access modifier?

   A: Protected

   B: Void

   C: Public

   D: Private

   Ans: B

   Explanation:

   Public, private, protected and default are the access modifiers.

3. What will be the output of the following Java program?

   
   final class A 
   {
       int i;
   }    
   class B extends A 
   {
       int j;
       System.out.println(j + " " + i);  
   }    
   class inheritance 
   {
       public static void main(String args[])
       {
           B obj = new B();
           obj.display();     
       }
   }
       

   A: 2 2

   B: 3 3

   C: Runtime Error

   D: Compilation Error

   Ans: D

   Explanation:

   Class A has been declared final hence it cannot be inherited by any other class. Hence class B does not have member i, giving compilation error.

   Output:

   
   $ javac inheritance.java
   Exception in thread "main" java.lang.Error: Unresolved compilation problem: 
       i cannot be resolved or is not a field
       

4. What is the numerical range of a char data type in Java?

   A: 0 to 256

   B: -128 to 127

   C: 0 to 65535

   D: 0 to 32767

   Ans: C

   Explanation:

   Char occupies 16-bit in memory, so it supports 216 i:e from 0 to 65535.

5. Which class provides system independent server side implementation?

   A: Server

   B: ServerReader

   C: Socket

   D: ServerSocket

   Ans: D

   Explanation:

   ServerSocket is a java.net class which provides system independent implementation of server side socket connection.

6. What will be the output of the following Java code?

   
   class newthread extends Thread
   {
       Thread t;
       newthread()
       {
           t1 = new Thread(this, "Thread_1");
           t2 = new Thread(this, "Thread_2");
           t1.start();
           t2.start();
       }
       public void run()
       {
           t2.setPriority(Thread.MAX_PRIORITY);    
           System.out.print(t1.equals(t2));
       }    
   }
   class multithreaded_programing
   {
       public static void main(String args[])
       {
           new newthread();        
       }
   }
       

   A: truetrue

   B: falsefalse

   C: true

   D: false

   Ans: B

   Explanation:

   This program was previously done by using Runnable interface, here we have used Thread class. This shows both methods are equivalent, we can use any of them to create a thread.

   Output:

   
   $ javac multithreaded_programing.java
   $ java multithreaded_programing
   falsefalse
       

7. When do exceptions in Java arise in the code sequence?

       a) Run Time
       b) Compilation Time
       c) Can Occur Any Time
       d) None of the mentioned
       

   Answer: a) Run Time Explanation: Exceptions in Java are run-time errors that occur when the program is executing.
8. Which of these keywords is not a part of exception handling?

       a) try
       b) finally
       c) thrown
       d) catch
       

   Answer: c) thrown Explanation: The five main keywords for exception handling are: try, catch, throws, throw, and finally.
9. Which of these keywords must be used to monitor for exceptions?

       a) try
       b) finally
       c) throw
       d) catch
       

   Answer: a) try Explanation: The try block is used to monitor for exceptions in Java.
10. Which of these keywords must be used to handle the exception thrown by try block in some rational manner?

        a) try
        b) finally
        c) throw
        d) catch
        

    Answer: d) catch Explanation: If an exception occurs in the try block, it is handled by the catch block.
11. Which of these keywords is used to manually throw an exception?

        a) try
        b) finally
        c) throw
        d) catch
        

    Answer: c) throw Explanation: The throw keyword is used to manually throw an exception in Java.
12. What will be the output of the following Java program?

        class exception_handling 
        {
            public static void main(String args[]) 
            {
                try 
                {
                    System.out.print("Hello" + " " + 1 / 0);
                }
                catch(ArithmeticException e) 
                {
                    System.out.print("World");
                }
            }
        }
        

    Answer: b) World Explanation: The 1 / 0 causes an ArithmeticException, which is caught by the catch block, printing "World". Output:

        $ javac exception_handling.java
        $ java exception_handling
        World