import java.io.*;

public class ThreadTeste extends Thread
{
 private Point2d i;
 private char ch;

 public static void main(String[] args)
   {
    Point2d temp = new Point2d (10, 0);

    System.out.println ("Hello vaue of point is : " + temp);
    ThreadTeste tt = new ThreadTeste('a', temp);
    ThreadTeste tt2 = new ThreadTeste('b', temp);
    ThreadTeste tt3 = new ThreadTeste('c', temp);
    ThreadTeste tt4 = new ThreadTeste('d', temp);

    System.out.println ("Before Joins- Point is: " + temp);
    try{
    tt.join();
       }
     catch (Exception e)
      {}
    try{
    tt2.join();
       }
     catch (Exception e)
      {}
    try{
    tt3.join();
       }
     catch (Exception e)
      {}
    try{
    tt4.join();
       }
     catch (Exception e)
      {}

    System.out.println ("Goodbye- Point is: " + temp);
    }


 public ThreadTeste(char cParm, Point2d iparm)
   {
    //i = 10;
    i = iparm;
    ch = cParm;

    start();

    //i += 2; 
    //i.setX(i.getX() + 2);


    System.out.println ("From original thread " + ch + ", i: " + i);
   }

 public void run ()
   {
    int y = 0;

    if (ch == 'a')
       y = 1;
    if (ch == 'b')
       y = 2;
    if (ch == 'c')
       y = -2;
    if (ch == 'd')
       y = -1;

    System.out.println ("From new thread " + ch + ", i: " + i); 

    for (int j = 0 ; j < 1000000; j++)
    {
      // i.setX(i.getX() + y);
      modifyI2(y);
    }

    System.out.println ("Goodbye from thread " + ch + ", i: " + i);
   }
 

  // improper use of synchronized to avoid data collisions on 
  //  the shared variable i.  The code snychronizes on the instances
  //  of the thread class and not on the instance of i
  synchronized public void modifyI (int deta)
    {
     int temp = i.getX();
     temp = temp + deta;
     i.setX(temp);
   } 


  // this shows proper usage of synchronization on  the instance
  //   of the shared variable i 
  public void modifyI2(int deta)
    {
     synchronized (i)
       {
        int temp = i.getX();
        temp = temp + deta;
        i.setX(temp);
       }
   } 


}