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  • Question
  • What will be the output of the program?
    public class X 
    {
        public static void main(String [] args) 
        {
            String names [] = new String[5];
            for (int x=0; x < args.length; x++)
                names[x] = args[x];
            System.out.println(names[2]);
        }
    }
    
    and the command line invocation is

    > java X a b


  • Options
  • A. names
  • B. null
  • C. Compilation fails
  • D. An exception is thrown at runtime

  • Correct Answer
  • null 

    Explanation
    The names array is initialized with five null elements. Then elements 0 and 1 are assigned the String values "a" and "b" respectively (the command-line arguments passed to main). Elements of names array 2, 3, and 4 remain unassigned, so they have a value of null.

  • Language Fundamentals problems


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    • 1. What will be the output of the program?
      public class CommandArgsThree 
      {
          public static void main(String [] args) 
          {
              String [][] argCopy = new String[2][2];
              int x;
              argCopy[0] = args;
              x = argCopy[0].length;
              for (int y = 0; y < x; y++) 
              {
                  System.out.print(" " + argCopy[0][y]);
              }
          }
      }
      
      and the command-line invocation is

      > java CommandArgsThree 1 2 3


    • Options
    • A. 0 0
    • B. 1 2
    • C. 0 0 0
    • D. 1 2 3
    • Discuss
    • 2. Which of these will create and start this thread?
      public class MyRunnable implements Runnable 
      {
          public void run() 
          {
              // some code here
          }
      }
      

    • Options
    • A. new Runnable(MyRunnable).start();
    • B. new Thread(MyRunnable).run();
    • C. new Thread(new MyRunnable()).start();
    • D. new MyRunnable().start();
    • Discuss
    • 3. Which of the following will directly stop the execution of a Thread?

    • Options
    • A. wait()
    • B. notify()
    • C. notifyall()
    • D. exits synchronized code
    • Discuss
    • 4. What is the name of the method used to start a thread execution?

    • Options
    • A. init();
    • B. start();
    • C. run();
    • D. resume();
    • Discuss
    • 5. Assume the following method is properly synchronized and called from a thread A on an object B:

      wait(2000);

      After calling this method, when will the thread A become a candidate to get another turn at the CPU?


    • Options
    • A. After thread A is notified, or after two seconds.
    • B. After the lock on B is released, or after two seconds.
    • C. Two seconds after thread A is notified.
    • D. Two seconds after lock B is released.
    • Discuss
    • 6. What will be the output of the program, if this code is executed with the command line:

      > java F0091 world

      public class F0091 
      {    
          public void main( String[] args ) 
          {  
              System.out.println( "Hello" + args[0] ); 
          } 
      }
      

    • Options
    • A. Hello
    • B. Hello Foo91
    • C. Hello world
    • D. The code does not run.
    • Discuss
    • 7. What will be the output of the program?
      public class CommandArgsTwo 
      {
          public static void main(String [] argh) 
          {
              int x;
              x = argh.length;
              for (int y = 1; y <= x; y++) 
              {
                  System.out.print(" " + argh[y]);
              }
          }
      }
      
      and the command-line invocation is

      > java CommandArgsTwo 1 2 3


    • Options
    • A. 0 1 2
    • B. 1 2 3
    • C. 0 0 0
    • D. An exception is thrown at runtime
    • Discuss
    • 8. What will be the output of the program?
      public class TestDogs 
      {
          public static void main(String [] args) 
          {
              Dog [][] theDogs = new Dog[3][];
              System.out.println(theDogs[2][0].toString());
          }
      }
      class Dog { }
      

    • Options
    • A. null
    • B. theDogs
    • C. Compilation fails
    • D. An exception is thrown at runtime
    • Discuss
    • 9. What will be the output of the program?
      public class Test 
      {
          public static void main(String [] args) 
          {
              signed int x = 10;
              for (int y=0; y<5; y++, x--)
                  System.out.print(x + ", ");
          }
      }
      

    • Options
    • A. 10, 9, 8, 7, 6,
    • B. 9, 8, 7, 6, 5,
    • C. Compilation fails.
    • D. An exception is thrown at runtime.
    • Discuss
    • 10. What will be the output of the program?
      public class CommandArgs 
      {
          public static void main(String [] args) 
          {
              String s1 = args[1];
              String s2 = args[2];
              String s3 = args[3];
              String s4 = args[4];
              System.out.print(" args[2] = " + s2);
          }
      }
      
      and the command-line invocation is

      > java CommandArgs 1 2 3 4


    • Options
    • A. args[2] = 2
    • B. args[2] = 3
    • C. args[2] = null
    • D. An exception is thrown at runtime.
    • Discuss


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