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  • Question
  • What will be the output of the program?
    public class Test 
    { 
        public static void main(String[] args) 
        {
            final StringBuffer a = new StringBuffer(); 
            final StringBuffer b = new StringBuffer(); 
    
            new Thread() 
            { 
                public void run() 
                {
                    System.out.print(a.append("A")); 
                    synchronized(b) 
                    { 
                        System.out.print(b.append("B")); 
                    } 
                } 
            }.start(); 
                
            new Thread() 
            {
                public void run() 
                {
                    System.out.print(b.append("C")); 
                    synchronized(a) 
                    {
                        System.out.print(a.append("D")); 
                    } 
                } 
            }.start(); 
        } 
    }
    


  • Options
  • A. ACCBAD
  • B. ABBCAD
  • C. CDDACB
  • D. Indeterminate output

  • Correct Answer
  • Indeterminate output 

    Explanation
    It gives different output while executing the same compiled code at different times.

    Java.lang Class problems


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    • 1. What will be the output of the program?
      public class ExamQuestion7 
      {  
          static int j; 
          static void methodA(int i)
          {
              boolean b; 
              do
              { 
                  b = i<10 | methodB(4); /* Line 9 */
                  b = i<10 || methodB(8);  /* Line 10 */
              }while (!b); 
          } 
          static boolean methodB(int i)
          {
              j += i; 
              return true; 
          } 
          public static void main(String[] args)
          {
              methodA(0); 
              System.out.println( "j = " + j ); 
          } 
      }
      

    • Options
    • A. j = 0
    • B. j = 4
    • C. j = 8
    • D. The code will run with no output
    • Discuss
    • 2. 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
    • 3. What will be the output of the program?
      public class Test178 
      { 
          public static void main(String[] args) 
          {
              String s = "foo"; 
              Object o = (Object)s; 
              if (s.equals(o)) 
              { 
                  System.out.print("AAA"); 
              } 
              else 
              {
                  System.out.print("BBB"); 
              } 
              if (o.equals(s)) 
              {
                  System.out.print("CCC"); 
              } 
              else 
              {
                  System.out.print("DDD"); 
              } 
          } 
      }
      

    • Options
    • A. AAACCC
    • B. AAADDD
    • C. BBBCCC
    • D. BBBDDD
    • Discuss
    • 4. What will be the output of the program?
      public class Test138 
      { 
          public static void stringReplace (String text) 
          {
              text = text.replace ('j' , 'c'); /* Line 5 */
          } 
          public static void bufferReplace (StringBuffer text) 
          { 
              text = text.append ("c");  /* Line 9 */
          } 
          public static void main (String args[]) 
          { 
              String textString = new String ("java"); 
              StringBuffer textBuffer = new StringBuffer ("java"); /* Line 14 */
              stringReplace(textString); 
              bufferReplace(textBuffer); 
              System.out.println (textString + textBuffer); 
          } 
      }
      

    • Options
    • A. java
    • B. javac
    • C. javajavac
    • D. Compile error
    • Discuss
    • 5. 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
    • 6. 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
    • 7. 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
    • 8. What will be the output of the program?
      String a = "ABCD"; 
      String b = a.toLowerCase(); 
      b.replace('a','d'); 
      b.replace('b','c'); 
      System.out.println(b);
      

    • Options
    • A. abcd
    • B. ABCD
    • C. dccd
    • D. dcba
    • Discuss
    • 9. 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
    • 10. What will be the output of the program?
      interface Foo141 
      { 
          int k = 0; /* Line 3 */
      } 
      public class Test141 implements Foo141 
      {
          public static void main(String args[]) 
          {
              int i; 
              Test141 test141 = new Test141(); 
              i = test141.k; /* Line 11 */
              i = Test141.k; 
              i = Foo141.k; 
          } 
      }
      

    • Options
    • A. Compilation fails.
    • B. Compiles and runs ok.
    • C. Compiles but throws an Exception at runtime.
    • D. Compiles but throws a RuntimeException at runtime.
    • Discuss


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