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Home Java Programming Objects and Collections See What Others Are Saying!
  • Question
  • Which of the following statements about the hashcode() method are incorrect?

    1. The value returned by hashcode() is used in some collection classes to help locate objects.
    2. The hashcode() method is required to return a positive int value.
    3. The hashcode() method in the String class is the one inherited from Object.
    4. Two new empty String objects will produce identical hashcodes.


  • Options
  • A. 1 and 2
  • B. 2 and 3
  • C. 3 and 4
  • D. 1 and 4

  • Correct Answer
  • 2 and 3 

    Explanation
    (2) is an incorrect statement because there is no such requirement.

    (3) is an incorrect statement and therefore a correct answer because the hashcode for a string is computed from the characters in the string.


    More questions

    • 1. What will be the output of the program?
      public class BoolTest 
      {
          public static void main(String [] args) 
          {
              int result = 0;
      
              Boolean b1 = new Boolean("TRUE");
              Boolean b2 = new Boolean("true");
              Boolean b3 = new Boolean("tRuE");
              Boolean b4 = new Boolean("false");
      
              if (b1 == b2)  /* Line 10 */
                  result = 1;
              if (b1.equals(b2) ) /* Line 12 */
                  result = result + 10;
              if (b2 == b4)  /* Line 14 */
                  result = result + 100;
              if (b2.equals(b4) ) /* Line 16 */
                  result = result + 1000;
              if (b2.equals(b3) ) /* Line 18 */
                  result = result + 10000;
      
              System.out.println("result = " + result);
          }
      }
      

    • Options
    • A. 0
    • B. 1
    • C. 10
    • D. 10010
    • Discuss
    • 2. What will be the output of the program?
      int i = 0, j = 5; 
      tp: for (;;) 
          {
              i++;  
              for (;;) 
              {
                  if(i > --j) 
                  {
                      break tp; 
                  } 
              } 
              System.out.println("i =" + i + ", j = " + j);
      

    • Options
    • A. i = 1, j = 0
    • B. i = 1, j = 4
    • C. i = 3, j = 4
    • D. Compilation fails.
    • Discuss
    • 3. Which two statements are equivalent?

      1. 3/2
      2. 3<2
      3. 3*4
      4. 3<<2

    • Options
    • A. 1 and 2
    • B. 2 and 3
    • C. 3 and 4
    • D. 1 and 4
    • Discuss
    • 4. Which three guarantee that a thread will leave the running state?

      1. yield()
      2. wait()
      3. notify()
      4. notifyAll()
      5. sleep(1000)
      6. aLiveThread.join()
      7. Thread.killThread()

    • Options
    • A. 1, 2 and 4
    • B. 2, 5 and 6
    • C. 3, 4 and 7
    • D. 4, 5 and 7
    • Discuss
    • 5. What will be the output of the program?
      int i = 1, j = 10; 
      do 
      {
          if(i > j) 
          {
              break; 
          } 
          j--; 
      } while (++i < 5); 
      System.out.println("i = " + i + " and j = " + j);
      

    • Options
    • A. i = 6 and j = 5
    • B. i = 5 and j = 5
    • C. i = 6 and j = 4
    • D. i = 5 and j = 6
    • Discuss
    • 6. What will be the output of the program?
      public class Q126 implements Runnable 
      { 
          private int x; 
          private int y; 
      
          public static void main(String [] args) 
          { 
              Q126 that = new Q126(); 
              (new Thread(that)).start( ); /* Line 8 */
              (new Thread(that)).start( ); /* Line 9 */
          } 
          public synchronized void run( ) /* Line 11 */
          { 
              for (;;) /* Line 13 */
              { 
                  x++; 
                  y++; 
                  System.out.println("x = " + x + "y = " + y); 
              } 
          } 
      }
      

    • Options
    • A. An error at line 11 causes compilation to fail
    • B. Errors at lines 8 and 9 cause compilation to fail.
    • C. The program prints pairs of values for x and y that might not always be the same on the same line (for example, "x=2, y=1")
    • D. The program prints pairs of values for x and y that are always the same on the same line (for example, "x=1, y=1". In addition, each value appears once (for example, "x=1, y=1" followed by "x=2, y=2")
    • Discuss
    • 7. Which cause a compiler error?

    • Options
    • A. int[ ] scores = {3, 5, 7};
    • B. int [ ][ ] scores = {2,7,6}, {9,3,45};
    • C. String cats[ ] = {"Fluffy", "Spot", "Zeus"};
    • D. boolean results[ ] = new boolean [] {true, false, true};
    • E. Integer results[ ] = {new Integer(3), new Integer(5), new Integer(8)};
    • Discuss
    • 8. What will be the output of the program?
      class SSBool 
      {
          public static void main(String [] args) 
          {
              boolean b1 = true;
              boolean b2 = false;
              boolean b3 = true;
              if ( b1 & b2 | b2 & b3 | b2 ) /* Line 8 */
                  System.out.print("ok ");
              if ( b1 & b2 | b2 & b3 | b2 | b1 ) /*Line 10*/
                  System.out.println("dokey");
          }
      }
      

    • Options
    • A. ok
    • B. dokey
    • C. ok dokey
    • D. No output is produced
    • E. Compilation error
    • Discuss
    • 9. Which will legally declare, construct, and initialize an array?

    • Options
    • A. int [] myList = {"1", "2", "3"};
    • B. int [] myList = (5, 8, 2);
    • C. int myList [] [] = {4,9,7,0};
    • D. int myList [] = {4, 3, 7};
    • Discuss
    • 10. What will be the output of the program?
      class BitShift 
      {
          public static void main(String [] args) 
          {
              int x = 0x80000000;
              System.out.print(x + " and  ");
              x = x >>> 31;
              System.out.println(x);
          }
      }
      

    • Options
    • A. -2147483648 and 1
    • B. 0x80000000 and 0x00000001
    • C. -2147483648 and -1
    • D. 1 and -2147483648
    • Discuss


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