Implementation of 2PL Protocol in java.

Implementation of 2PL Protocol in java.


import java.io.*;
import java.util.*;

class Account
{
    String name;
    int amount,lock;
   
    Account(String name,int amount,int lock)
    {
    this.name=name;
    this.amount=amount;
    this.lock=lock;
    }
   
    public void deposit(int amt)
    {
        amount +=amt;
    }
   
    public void withdraw(int amt)
    {
        if((amount-amt)<0)
        {
            System.out.println("Transaction Cannot proceed : Not Enough Balance in Account"+name);
            System.exit(0);
        }
        amount -=amt;
       
    }
   
    public int balance()
    {
        return amount;
    }
}

class Transaction implements Runnable
{
    private Thread t=null;
    String id;
    Account from,to;
    int amount;
   
   
    Transaction(String id,Account from,Account to,int amount)
    {
        this.id=id;
        this.from=from;
        this.to=to;
        this.amount=amount;
    }

    public void acquireLock(Account x,int type)
    {
        x.lock=type;
    }

    public void releaseLock(Account x)
    {
        x.lock=0;
    }

     public void  run() {
      System.out.println("Running Transaction" +  id );
      try {
         acquireLock(from,3);
         acquireLock(to,3);
         from.withdraw(amount);
         to.deposit(amount);
         System.out.println("Transaction "+id+" is completed");
         releaseLock(from);
     releaseLock(to);
         System.out.println("Balance of Account "+from.name+" is "+from.balance());
         System.out.println("Balance of Account "+to.name+" is "+to.balance());
            // Let the thread sleep for a while.
         Thread.sleep(50);
           
         }
      catch (InterruptedException e) {
         System.out.println("Transaction " +  id + " interrupted.");
     }
     System.out.println("Transaction " +  id + " exiting.");
   }
  
  
   public void start ()
   {
      System.out.println("Starting Transaction " +  id );
     
      while(!(from.lock==0 && to.lock==0));
     
          if(t==null)
          {
            t = new Thread(this,this.id);
            t.start ();
        }
     
   }
  
   
}
public class twophase
{
   public static void main(String args[])
   {
  
      Account A=new Account("A",500,0);
      Account B=new Account("B",800,0);
      Account C=new Account("C",900,0);
      Transaction T1 = new Transaction( "T-1",A,B,200);
      T1.start();
     
      Transaction T2 = new Transaction( "T-2",C,B,500);
      T2.start();
     
      Transaction T3 = new Transaction( "T-3",A,B,400);
      T3.start();
   }  
}