Multithreading

import java.util.Scanner;
class Account
{
int bal;
Account (int b)
{
bal=b;
}
boolean isSufficientBal(int w)
{
if(bal>w)
{
return true;
}
else
{
return false;
}
}
void withdraw(int amt, String g1)
{
bal=bal-amt;
System.out.println(g1+"Transaction is successful.");
System.out.println(g1+"Current balance is "+bal);
}
}
class Customer implements Runnable
{
String m1;
Account x1;
Customer (Account j1, String h1)
{
x1 = j1;
m1 = h1;
}
public void run ()
{
Scanner s1 = new Scanner(System.in);
synchronized (x1)
{
System.out.println("Enter amount to withdraw for "+m1+":");
int amt = s1.nextInt();
if(x1.isSufficientBal(amt))
{
x1.withdraw(amt,m1);
}
else
{
System.out.println("Insufficient Balance ");
}
}
}
}
class ThreadSyn
{
public static void main (String [] args)
{
Account a1 = new Account (5000);
Customer c1 = new Customer (a1,"Amit");
Customer c2 = new Customer (a1,"sumit");
Thread t1 = new Thread (c1);
Thread t2 = new Thread (c2);
t1.start();
t2.start();

}
}