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  • Question
  • 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

  • Correct Answer
  • xyzabc 

    Explanation
    Line 2 creates a new String object with the value "XYZ", but this new object is immediately lost because there is no reference to it. Line 3 creates a new String object referenced by y. This new String object has the value "xyz" because there was no "Y" in the String object referred to by x. Line 4 creates a new String object, appends "abc" to the value "xyz", and refers y to the result.

    More questions

    • 1. What will be the output of the program?
      public class StringRef 
      {
          public static void main(String [] args) 
          {
              String s1 = "abc";
              String s2 = "def";
              String s3 = s2;   /* Line 7 */
              s2 = "ghi";
              System.out.println(s1 + s2 + s3);
          }
      }
      

    • Options
    • A. abcdefghi
    • B. abcdefdef
    • C. abcghidef
    • D. abcghighi
    • Discuss
    • 2. What will be the output of the program?
      public class ObjComp 
      {
          public static void main(String [] args ) 
          {
              int result = 0;
              ObjComp oc = new ObjComp();
              Object o = oc;
      
              if (o == oc)  
                  result = 1;
              if (o != oc)  
                  result = result + 10;
              if (o.equals(oc) )  
                  result = result + 100;
              if (oc.equals(o) )  
                  result = result + 1000;
      
              System.out.println("result = " + result);
          }
      }
      

    • Options
    • A. 1
    • B. 10
    • C. 101
    • D. 1101
    • Discuss
    • 3. What will be the output of the program?
      String d = "bookkeeper";
      d.substring(1,7);
      d = "w" + d;
      d.append("woo");  /* Line 4 */
      System.out.println(d);
      

    • Options
    • A. wookkeewoo
    • B. wbookkeeper
    • C. wbookkeewoo
    • D. Compilation fails.
    • Discuss
    • 4. What will be the output of the program?
      interface Count 
      {
          short counter = 0;
          void countUp();
      }
      public class TestCount implements Count 
      {
          public static void main(String [] args) 
          {
              TestCount t = new TestCount();
              t.countUp();
          }
          public void countUp() 
          {
              for (int x = 6; x>counter; x--, ++counter) /* Line 14 */
              {
                  System.out.print(" " + counter);
              }
          }
      }
      

    • Options
    • A. 0 1 2
    • B. 1 2 3
    • C. 0 1 2 3
    • D. 1 2 3 4
    • E. Compilation fails
    • Discuss
    • 5. Which three form part of correct array declarations?

      1. public int a [ ]
      2. static int [ ] a
      3. public [ ] int a
      4. private int a [3]
      5. private int [3] a [ ]
      6. public final int [ ] a

    • Options
    • A. 1, 3, 4
    • B. 2, 4, 5
    • C. 1, 2, 6
    • D. 2, 5, 6
    • Discuss
    • 6. What will be the output of the program?
      public class X 
      { 
          public static void main(String [] args) 
          {
              try 
              {
                  badMethod();  
                  System.out.print("A"); 
              }  
              catch (Exception ex) 
              {
                  System.out.print("B"); 
              }  
              finally 
              {
                  System.out.print("C"); 
              }  
              System.out.print("D"); 
          }  
          public static void badMethod() {} 
      } 
      

    • Options
    • A. AC
    • B. BC
    • C. ACD
    • D. ABCD
    • Discuss
    • 7. Which of the following line of code is suitable to start a thread?
      class X implements Runnable 
      { 
          public static void main(String args[]) 
          {
              /* Missing code? */
          } 
          public void run() {} 
      }
      

    • Options
    • A. Thread t = new Thread(X);
    • B. Thread t = new Thread(X); t.start();
    • C. X run = new X(); Thread t = new Thread(run); t.start();
    • D. Thread t = new Thread(); x.run();
    • Discuss
    • 8. What will be the output of the program?
      try 
      {
          Float f1 = new Float("3.0");
          int x = f1.intValue();
          byte b = f1.byteValue();
          double d = f1.doubleValue();
          System.out.println(x + b + d);
      }
      catch (NumberFormatException e) /* Line 9 */
      {
          System.out.println("bad number"); /* Line 11 */
      }
      

    • Options
    • A. 9.0
    • B. bad number
    • C. Compilation fails on line 9.
    • D. Compilation fails on line 11.
    • Discuss
    • 9. What will be the output of the program?
      String a = "newspaper";
      a = a.substring(5,7);
      char b = a.charAt(1);
      a = a + b;
      System.out.println(a);
      

    • Options
    • A. apa
    • B. app
    • C. apea
    • D. apep
    • Discuss
    • 10. Which statement is true?

    • Options
    • A. The notifyAll() method must be called from a synchronized context.
    • B. To call wait(), an object must own the lock on the thread.
    • C. The notify() method is defined in class java.lang.Thread.
    • D. The notify() method causes a thread to immediately release its locks.
    • Discuss


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