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Home Java Programming Declarations and Access Control See What Others Are Saying!
  • Question
  • What will be the output of the program?
    class Super 
    { 
        public Integer getLength() 
        {
            return new Integer(4); 
        } 
    } 
    
    public class Sub extends Super 
    { 
        public Long getLength() 
        {
            return new Long(5); 
        } 
    
        public static void main(String[] args) 
        { 
            Super sooper = new Super(); 
            Sub sub = new Sub(); 
            System.out.println( 
            sooper.getLength().toString() + "," + sub.getLength().toString() ); 
        } 
    }
    


  • Options
  • A. 4, 4
  • B. 4, 5
  • C. 5, 4
  • D. Compilation fails.

  • Correct Answer
  • Compilation fails. 

    Explanation
    Option D is correct, compilation fails - The return type of getLength( ) in the super class is an object of reference type Integer and the return type in the sub class is an object of reference type Long. In other words, it is not an override because of the change in the return type and it is also not an overload because the argument list has not changed.

    More questions

    • 1. Which two statements are equivalent?

      1. 16*4
      2. 16>>2
      3. 16/2^2
      4. 16>>>2

    • Options
    • A. 1 and 2
    • B. 2 and 4
    • C. 3 and 4
    • D. 1 and 3
    • Discuss
    • 2. What two statements are true about properly overridden hashCode() and equals() methods?

      1. hashCode() doesn't have to be overridden if equals() is.
      2. equals() doesn't have to be overridden if hashCode() is.
      3. hashCode() can always return the same value, regardless of the object that invoked it.
      4. equals() can be true even if it's comparing different objects.

    • Options
    • A. 1 and 2
    • B. 2 and 3
    • C. 3 and 4
    • D. 1 and 3
    • Discuss
    • 3. Which is a valid keyword in java?

    • Options
    • A. interface
    • B. string
    • C. Float
    • D. unsigned
    • Discuss
    • 4. What will be the output of the program?
      int i = 1, j = 10; 
      do 
      {
          if(i++ > --j) /* Line 4 */
          {
              continue; 
          } 
      } while (i < 5); 
      System.out.println("i = " + i + "and j = " + j); /* Line 9 */
      

    • Options
    • A. i = 6 and j = 5
    • B. i = 5 and j = 5
    • C. i = 6 and j = 6
    • D. i = 5 and j = 6
    • Discuss
    • 5. What will be the output of the program?
      int i = 0; 
      while(1) 
      {
          if(i == 4) 
          {
              break;
          } 
          ++i; 
      } 
      System.out.println("i = " + i);
      

    • Options
    • A. i = 0
    • B. i = 3
    • C. i = 4
    • D. Compilation fails.
    • Discuss
    • 6. What will be the output of the program?
      public class Test 
      {
          public int aMethod()
          {
              static int i = 0;
              i++;
              return i;
          }
          public static void main(String args[])
          {
              Test test = new Test();
              test.aMethod();
              int j = test.aMethod();
              System.out.println(j);
          }
      }
      

    • Options
    • A. 0
    • B. 1
    • C. 2
    • D. Compilation fails.
    • Discuss
    • 7. What will be the output of the program?
      int x = l, y = 6; 
      while (y--) 
      {
          x++; 
      } 
      System.out.println("x = " + x +" y = " + y);
      

    • Options
    • A. x = 6 y = 0
    • B. x = 7 y = 0
    • C. x = 6 y = -1
    • D. Compilation fails.
    • Discuss
    • 8. What will be the output of the program?
      class MyThread extends Thread 
      { 
          MyThread() {} 
          MyThread(Runnable r) {super(r); } 
          public void run() 
          { 
              System.out.print("Inside Thread ");
          } 
      } 
      class MyRunnable implements Runnable 
      { 
          public void run() 
          { 
              System.out.print(" Inside Runnable"); 
          } 
      } 
      class Test 
      {  
          public static void main(String[] args) 
          { 
              new MyThread().start(); 
              new MyThread(new MyRunnable()).start(); 
          } 
      }
      

    • Options
    • A. Prints "Inside Thread Inside Thread"
    • B. Prints "Inside Thread Inside Runnable"
    • C. Does not compile
    • D. Throws exception at runtime
    • Discuss
    • 9. Which statement is true?

    • Options
    • A. Assertions can be enabled or disabled on a class-by-class basis.
    • B. Conditional compilation is used to allow tested classes to run at full speed.
    • C. Assertions are appropriate for checking the validity of arguments in a method.
    • D. The programmer can choose to execute a return statement or to throw an exception if an assertion fails.
    • Discuss
    • 10. What will be the output of the program?
      class Two 
      {
          byte x;
      }
      
      class PassO 
      {
          public static void main(String [] args) 
          {
              PassO p = new PassO();
              p.start();
          }
      
          void start() 
          {
              Two t = new Two();
              System.out.print(t.x + " ");
              Two t2 = fix(t);
              System.out.println(t.x + " " + t2.x);
          }
      
          Two fix(Two tt) 
          {
              tt.x = 42;
              return tt;
          }
      }
      

    • Options
    • A. null null 42
    • B. 0 0 42
    • C. 0 42 42
    • D. 0 0 0
    • Discuss


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