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  • Question
  • 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

  • Correct Answer
  • j = 4 

    Explanation
    The lines to watch here are lines 9 & 10. Line 9 features the non-shortcut version of the OR operator so both of its operands will be evaluated and therefore methodB(4) is executed.

    However line 10 has the shortcut version of the OR operator and if the 1st of its operands evaluates to true (which in this case is true), then the 2nd operand isn't evaluated, so methodB(8) never gets called.

    The loop is only executed once, b is initialized to false and is assigned true on line 9. Thus j = 4.


    More questions

    • 1. Which is a reserved word in the Java programming language?

    • Options
    • A. method
    • B. native
    • C. subclasses
    • D. reference
    • E. array
    • Discuss
    • 2. Which statement is true for the class java.util.ArrayList?

    • Options
    • A. The elements in the collection are ordered.
    • B. The collection is guaranteed to be immutable.
    • C. The elements in the collection are guaranteed to be unique.
    • D. The elements in the collection are accessed using a unique key.
    • Discuss
    • 3. 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
    • Discuss
    • 4. Which is true about a method-local inner class?

    • Options
    • A. It must be marked final.
    • B. It can be marked abstract.
    • C. It can be marked public.
    • D. It can be marked static.
    • Discuss
    • 5. Given that all methods of class FileOutputStream, including close(), throw an IOException, which of these is true?
      import java.io.*;
      public class MyProgram 
      {
          public static void main(String args[])
          {
              FileOutputStream out = null;
              try 
              {
                  out = new FileOutputStream("test.txt");
                  out.write(122);
              }
              catch(IOException io) 
              {
                  System.out.println("IO Error.");
              }
              finally 
              {
                  out.close();
              }
          }
      }
      

    • Options
    • A. This program will compile successfully.
    • B. This program fails to compile due to an error at line 4.
    • C. This program fails to compile due to an error at line 6.
    • D. This program fails to compile due to an error at line 18.
    • Discuss
    • 6. What will be the output of the program?
      public class Test 
      {
          public static void main(String [] args) 
          {
              int I = 1;
              do while ( I < 1 )
              System.out.print("I is " + I);
              while ( I > 1 ) ;
          }
      }
      

    • Options
    • A. I is 1
    • B. I is 1 I is 1
    • C. No output is produced.
    • D. Compilation error
    • Discuss
    • 7. What will be the output of the program?
      class MyThread extends Thread 
      {
          public static void main(String [] args) 
          {
              MyThread t = new MyThread();
              Thread x = new Thread(t);
              x.start(); /* Line 7 */
          }
          public void run() 
          {
              for(int i = 0; i < 3; ++i) 
              {
                  System.out.print(i + "..");
              }
          }
      }
      

    • Options
    • A. Compilation fails.
    • B. 1..2..3..
    • C. 0..1..2..3..
    • D. 0..1..2..
    • Discuss
    • 8. Which of the following is/are legal method declarations?

      1. protected abstract void m1();
      2. static final void m1(){}
      3. synchronized public final void m1() {}
      4. private native void m1();

    • Options
    • A. 1 and 3
    • B. 2 and 4
    • C. 1 only
    • D. All of them are legal declarations.
    • Discuss
    • 9. Which three statements are true?
      1. f1 == f2
      2. f1 == f3
      3. f2 == f1[1]
      4. x == f1[0]
      5. f == f1[0]
      import java.awt.Button;
      class CompareReference 
      {
          public static void main(String [] args) 
          {
              float f = 42.0f;
              float [] f1 = new float[2];
              float [] f2 = new float[2];
              float [] f3 = f1;
              long x = 42;
              f1[0] = 42.0f;
          }
      }
      

    • Options
    • A. 1, 2 and 3
    • B. 2, 4 and 5
    • C. 3, 4 and 5
    • D. 1, 4 and 5
    • Discuss
    • 10. Which one create an anonymous inner class from within class Bar?
      class Boo 
      {
          Boo(String s) { }
          Boo() { }
      }
      class Bar extends Boo 
      {
          Bar() { }
          Bar(String s) {super(s);}
          void zoo() 
          {
          // insert code here
          }
      }
      

    • Options
    • A. Boo f = new Boo(24) { };
    • B. Boo f = new Bar() { };
    • C. Bar f = new Boo(String s) { };
    • D. Boo f = new Boo.Bar(String s) { };
    • Discuss


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