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Home Java Programming Declarations and Access Control See What Others Are Saying!
  • Question
  • 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

  • Correct Answer
  • Compilation fails 

    Explanation
    The code will not compile because the variable counter is an interface variable that is by default final static. The compiler will complain at line 14 when the code attempts to increment counter.

    More questions

    • 1. When is the B object, created in line 3, eligible for garbage collection?
      void start() {  
          A a = new A(); 
          B b = new B(); 
          a.s(b);  
          b = null; /* Line 5 */
          a = null;  /* Line 6 */
          System.out.println("start completed"); /* Line 7 */
      } 
      

    • Options
    • A. after line 5
    • B. after line 6
    • C. after line 7
    • D. There is no way to be absolutely certain.
    • Discuss
    • 2. Which is a reserved word in the Java programming language?

    • Options
    • A. method
    • B. native
    • C. subclasses
    • D. reference
    • E. array
    • Discuss
    • 3. 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
    • 4. 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
    • 5. 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
    • 6. 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
    • 7. 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
    • 8. 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
    • 9. 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
    • 10. 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


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