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  • Question
  • What will be the output of the program?
    public class Test 
    {  
        public static void main(String args[]) 
        { 
            int i = 1, j = 0; 
            switch(i) 
            { 
                case 2: j += 6; 
                case 4: j += 1; 
                default: j += 2; 
                case 0: j += 4; 
            } 
            System.out.println("j = " + j); 
        } 
    }
    


  • Options
  • A. j = 0
  • B. j = 2
  • C. j = 4
  • D. j = 6

  • Correct Answer
  • j = 6 

    Explanation
    Because there are no break statements, the program gets to the default case and adds 2 to j, then goes to case 0 and adds 4 to the new j. The result is j = 6.

    More questions

    • 1. Which of the following will directly stop the execution of a Thread?

    • Options
    • A. wait()
    • B. notify()
    • C. notifyall()
    • D. exits synchronized code
    • Discuss
    • 2. What will be the output of the program?
      public class Test107 implements Runnable 
      { 
          private int x; 
          private int y; 
      
          public static void main(String args[]) 
          {
              Test107 that = new Test107(); 
              (new Thread(that)).start(); 
              (new Thread(that)).start(); 
          } 
          public synchronized void run() 
          {
              for(int i = 0; i < 10; i++) 
              { 
                  x++; 
                  y++; 
                  System.out.println("x = " + x + ", y = " + y); /* Line 17 */
              } 
          } 
      } 
      

    • Options
    • A. Compilation error.
    • B. Will print in this order: x = 1 y = 1 x = 2 y = 2 x = 3 y = 3 x = 4 y = 4 x = 5 y = 5... but the output will be produced by both threads running simultaneously.
    • C. Will print in this order: x = 1 y = 1 x = 2 y = 2 x = 3 y = 3 x = 4 y = 4 x = 5 y = 5... but the output will be produced by first one thread then the other. This is guaranteed by the synchronised code.
    • D. Will print in this order x = 1 y = 2 x = 3 y = 4 x = 5 y = 6 x = 7 y = 8...
    • Discuss
    • 3. What will be the output of the program?
      String x = new String("xyz");
      String y = "abc";
      x = x + y;
      
      How many String objects have been created?

    • Options
    • A. 2
    • B. 3
    • C. 4
    • D. 5
    • Discuss
    • 4. What will be the output of the program?
      public class SqrtExample 
      {
          public static void main(String [] args) 
          {
              double value = -9.0;
              System.out.println( Math.sqrt(value));
          }
      }
      

    • Options
    • A. 3.0
    • B. -3.0
    • C. NaN
    • D. Compilation fails.
    • Discuss
    • 5. Which two are valid constructors for Thread?

      1. Thread(Runnable r, String name)
      2. Thread()
      3. Thread(int priority)
      4. Thread(Runnable r, ThreadGroup g)
      5. Thread(Runnable r, int priority)

    • Options
    • A. 1 and 3
    • B. 2 and 4
    • C. 1 and 2
    • D. 2 and 5
    • Discuss
    • 6. Which collection class allows you to associate its elements with key values, and allows you to retrieve objects in FIFO (first-in, first-out) sequence?

    • Options
    • A. java.util.ArrayList
    • B. java.util.LinkedHashMap
    • C. java.util.HashMap
    • D. java.util.TreeMap
    • Discuss
    • 7. What will be the output of the program?
      String x = "xyz";
      x.toUpperCase(); /* Line 2 */
      String y = x.replace('Y', 'y');
      y = y + "abc";
      System.out.println(y);
      

    • Options
    • A. abcXyZ
    • B. abcxyz
    • C. xyzabc
    • D. XyZabc
    • Discuss
    • 8. What will be the output of the program?
      public class SwitchTest 
      {  
          public static void main(String[] args) 
          {
              System.out.println("value =" + switchIt(4)); 
          } 
          public static int switchIt(int x) 
          {
              int j = 1;  
              switch (x) 
              { 
                  case l: j++; 
                  case 2: j++;  
                  case 3: j++; 
                  case 4: j++; 
                  case 5: j++; 
                  default: j++; 
                  } 
              return j + x;  
          } 
      }
      

    • Options
    • A. value = 2
    • B. value = 4
    • C. value = 6
    • D. value = 8
    • Discuss
    • 9. What will be the output of the program?
      public class If2 
      {
          static boolean b1, b2;
          public static void main(String [] args) 
          {
              int x = 0;
              if ( !b1 ) /* Line 7 */
              {
                  if ( !b2 ) /* Line 9 */
                  {
                      b1 = true;
                      x++;
                      if ( 5 > 6 ) 
                      {
                          x++;
                      }
                      if ( !b1 ) 
                          x = x + 10;
                      else if ( b2 = true ) /* Line 19 */
                          x = x + 100;
                      else if ( b1 | b2 ) /* Line 21 */
                          x = x + 1000;
                  }
              }
              System.out.println(x);
          }
      }
      

    • Options
    • A. 0
    • B. 1
    • C. 101
    • D. 111
    • Discuss
    • 10. What will be the output of the program?
      public class A
      { 
          void A() /* Line 3 */
          {
              System.out.println("Class A"); 
          } 
          public static void main(String[] args) 
          { 
              new A(); 
          } 
      }
      

    • Options
    • A. Class A
    • B. Compilation fails.
    • C. An exception is thrown at line 3.
    • D. The code executes with no output.
    • Discuss


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