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  • Question
  • What will be the output of the program?
    public class X 
    {
        public static void main(String [] args) 
        {
            String names [] = new String[5];
            for (int x=0; x < args.length; x++)
                names[x] = args[x];
            System.out.println(names[2]);
        }
    }
    
    and the command line invocation is

    > java X a b


  • Options
  • A. names
  • B. null
  • C. Compilation fails
  • D. An exception is thrown at runtime

  • Correct Answer
  • null 

    Explanation
    The names array is initialized with five null elements. Then elements 0 and 1 are assigned the String values "a" and "b" respectively (the command-line arguments passed to main). Elements of names array 2, 3, and 4 remain unassigned, so they have a value of null.

  • More questions

    • 1. The following block of code creates a Thread using a Runnable target:
      Runnable target = new MyRunnable();
      Thread myThread = new Thread(target);
      
      Which of the following classes can be used to create the target, so that the preceding code compiles correctly?

    • Options
    • A. public class MyRunnable extends Runnable{public void run(){}}
    • B. public class MyRunnable extends Object{public void run(){}}
    • C. public class MyRunnable implements Runnable{public void run(){}}
    • D. public class MyRunnable implements Runnable{void run(){}}
    • Discuss
    • 2. What will be the output of the program?
      public class WaitTest 
      {
          public static void main(String [] args) 
          {
              System.out.print("1 ");
              synchronized(args)
              {
                  System.out.print("2 ");
                  try 
                  {
                          args.wait(); /* Line 11 */
                  }
                  catch(InterruptedException e){ }
              }
              System.out.print("3 ");
          }
      }
      

    • Options
    • A. It fails to compile because the IllegalMonitorStateException of wait() is not dealt with in line 11.
    • B. 1 2 3
    • C. 1 3
    • D. 1 2
    • Discuss
    • 3. Which two are equal?

      1. 32/4
      2. (8 >> 2) << 4
      3. 2^5
      4. 128 >>> 2
      5. 2 >> 5

    • Options
    • A. 1 and 2
    • B. 2 and 4
    • C. 1 and 3
    • D. 2 and 3
    • Discuss
    • 4. Which one of the following will declare an array and initialize it with five numbers?

    • Options
    • A. Array a = new Array(5);
    • B. int [] a = {23,22,21,20,19};
    • C. int a [] = new int[5];
    • D. int [5] array;
    • Discuss
    • 5. What allows the programmer to destroy an object x?

    • Options
    • A. x.delete()
    • B. x.finalize()
    • C. Runtime.getRuntime().gc()
    • D. Only the garbage collection system can destroy an object.
    • Discuss
    • 6. What will be the output of the program?
      class A 
      { 
          public A(int x){} 
      } 
      class B extends A { } 
      public class test 
      { 
          public static void main (String args []) 
          {
              A a = new B(); 
              System.out.println("complete"); 
          } 
      }
      

    • Options
    • A. It compiles and runs printing nothing
    • B. Compiles but fails at runtime
    • C. Compile Error
    • D. Prints "complete"
    • Discuss
    • 7. What will be the output of the program?
      boolean bool = true; 
      if(bool = false) /* Line 2 */
      {
          System.out.println("a"); 
      } 
      else if(bool) /* Line 6 */
      {
          System.out.println("b"); 
      } 
      else if(!bool) /* Line 10 */
      {
          System.out.println("c"); /* Line 12 */
      } 
      else 
      {
          System.out.println("d"); 
      }
      

    • Options
    • A. a
    • B. b
    • C. c
    • D. d
    • Discuss
    • 8. What will be the output of the program?
      class s1 extends Thread
      { 
          public void run() 
          { 
              for(int i = 0; i < 3; i++) 
              { 
                  System.out.println("A"); 
                  System.out.println("B"); 
              } 
          } 
      } 
      class Test120 extends Thread 
      { 
          public void run() 
          { 
              for(int i = 0; i < 3; i++) 
              { 
                  System.out.println("C"); 
                  System.out.println("D"); 
              } 
          } 
          public static void main(String args[]) 
              { 
              s1 t1 = new s1(); 
              Test120 t2 = new Test120(); 
              t1.start(); 
              t2.start(); 
          } 
      }
      

    • Options
    • A. Compile time Error There is no start() method
    • B. Will print in this order AB CD AB...
    • C. Will print but not be able to predict the Order
    • D. Will print in this order ABCD...ABCD...
    • Discuss
    • 9. What will be the output of the program?
      class Exc0 extends Exception { } 
      class Exc1 extends Exc0 { } /* Line 2 */
      public class Test 
      {  
          public static void main(String args[]) 
          { 
              try 
              {  
                  throw new Exc1(); /* Line 9 */
              } 
              catch (Exc0 e0) /* Line 11 */
              {
                  System.out.println("Ex0 caught"); 
              } 
              catch (Exception e) 
              {
                  System.out.println("exception caught");  
              } 
          } 
      }
      

    • Options
    • A. Ex0 caught
    • B. exception caught
    • C. Compilation fails because of an error at line 2.
    • D. Compilation fails because of an error at line 9.
    • Discuss
    • 10. What will be the output of the program?
      class Test 
      {
          public static void main(String [] args) 
          {
              int x= 0;
              int y= 0;
              for (int z = 0; z < 5; z++) 
              {
                  if (( ++x > 2 ) && (++y > 2)) 
                  {
                      x++;
                  }
              }
              System.out.println(x + " " + y);
          }
      }
      

    • Options
    • A. 5 2
    • B. 5 3
    • C. 6 3
    • D. 6 4
    • Discuss


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