Java Quiz

    public class AQuestion
    {
         private int i = giveMeJ();
         private int j = 10;

         private int giveMeJ()
         {
              return j;
         }

         public static void main(String args[])
         {
              System.out.println((new AQuestion()).i);
         }
    }

Answers
 

1. Compiler error complaining about access restriction of private variables of AQuestion.
2. Compiler error complaining about forward referencing.
3. No Compilation error - The output is 0;
4. No Compilation error - The output is 10;

Question 12.

    public class AQuestion
    {
         public static void main(String args[])
         {
              System.out.println("Before Try");
              try
              {
              }
              catch(Throwable t)
              {
                   System.out.println("Inside Catch");
              }
              System.out.println("At the End");
         }
    }
 
 

1. Compiler error complaining about the catch block, where no Throwable object can ever be thrown.
2. Compiler error - Throwable Object can not be caught, only Exceptions must be caught.
3. No compiler error. The lines "Before Try" and "At the end" are printed on the screen.

public class AQuestion
{
     public static void main(String args[])
     {
          System.out.println("Before Try");
          try
          {
          }
          catch(java.io.IOException t)
          {
               System.out.println("Inside Catch");
          }
          System.out.println("At the End");
      }
}

1. Compiler error complaining about the catch block where no IOException object can ever be thrown.
2. Compiler error - IOException not found. It must be imported in the first line of the code.
3. No compiler error. The lines "Before Try" and "At the end" are printed on the screen.

        The class java.lang.Exception

           i.   Is public
           ii.  Extends Throwable
           iii. Implements Throwable
           iv.  Is serializable

         Read this piece of code carefully

if("String".trim() == "String".trim())
    System.out.println("Equal");
else
    System.out.println("Not Equal");

Answers

1. the code will compile an print "Equal".
2. the code will compile an print "Not Equal".
3. the code will cause a compiler error

         Read this piece of code carefully
 

if( "STRING".toUpperCase() == "STRING")
    System.out.println("Equal");
else
    System.out.println("Not Equal");

Answers

1. the code will compile an print "Equal".
2. the code will compile an print "Not Equal".
3. the code will cause a compiler error

Question 17.

        The following lines of code

             byte b = 0;
             b += 1;
 

1. results in b having the value 1.
2. causes a compiler error.
3. will require a cast (byte) before 1.

Question 18.

        The following express

            char c = -1;
 

1. will cause a compiler error as the range of character is between 0 and 2^16 - 1. Will request for an explicit cast.
2. will not cause a compiler error and c will have the value -1;
3. c will not represent any ascii character.
4. c will still be a unicode character.

Question 19.

        Which of the following statements are true?
 

1. A method can throw an Exception
2. A method can return an Exception

Question 20.

        All the  wrapper classes (Integer, Boolean, Float, Short, Long, Double and Character)
 

1. are public
2. are serializable
3. are immutatable
4. extend java.lang.Number
5. are final