Exercise 6   Name _______________ __/15

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1. (4 pts) What is one possible sequence of instructions executed for the complete program?
 

  1. public class sequencedThread
  2.  {
  3.     public static void main(String args[]) throws Exception
  4.     {
  5.          for (int i=1; i<=3; i++)
  6.                  new NumberedThread(i).start();
  7.  
  8.          System.out.println("main completed");
  9.     }
  10.  }
  11.  
  12.  class NumberedThread extends Thread
  13.  {
  14.     int n;
  15.  
  16.     public NumberedThread(int n)
  17.     {    this.n = n;
  18.     }
  19.  
  20.     public void run()
  21.     { 
  22.          System.out.println("  [Start Thread " + n + "]");
  23.          for(char ch='a'; ch<'d'; ch++)
  24.                  System.out.println("{Working Thread " + n + " <" + ch+ ">}");
  25.          System.out.println("  [Completed Thread " + n + "]");
  26.     }
  27.  }

2. (4 pts) What is reasonable expected output?
3. (1 pts) Are other outputs possible?
4. (4 pts) What is the sequence of instructions executed for the complete program?
 

  1. public class ex7
  2.  {
  3.     public static void main(String args[]) throws Exception
  4.     {  String string = new String("Go IUS");
  5.          for (int i=1; i<=3; i++)
  6.                  new NumberedThread(i, string).start();
  7.  
  8.          System.out.println("main completed");
  9.     }
  10.  }
  11.  
  12.  class NumberedThread extends Thread
  13.  {
  14.      int n;
  15.      String string;
  16.  
  17.     public NumberedThread(int n, String string)
  18.     {    this.n = n;
  19.           this.string = string;
  20.     }
  21.  
  22.     public void run()
  23.     { 
  24.          System.out.println("  [Start Thread " + n + "]");
  25.          synchronized(string) {
  26.                 for(char i='a'; i<'d'; i++)
  27.                     System.out.println("{Working Thread " + n + " <" + i + ">}");
  28.          }
  29.          System.out.println("  [Completed Thread " + n + "]");
  30.     }
  31.  }

5. (2 pts) Rearrange the following output into proper order for the above program. There are two mistakes. 

main completed
  [Start Thread 1]
{Working Thread 1 <b>}
{Working Thread 1 <a>}
{Working Thread 1 <c>}
  [Start Thread 2]
  [Start Thread 3]
  [Completed Thread 1]
{Working Thread 2 <a>}
{Working Thread 2 <b>}
{Working Thread 3 <a>}
{Working Thread 2 <c>}
  [Completed Thread 2]
{Working Thread 3 <b>}
{Working Thread 3 <c>}
  [Completed Thread 3]