public class Customer {

int amount = 10000;

synchronized void withdraw(int amount) {
System.out.println("going to withdraw..." + amount);  //Synchronized Method

if (this.amount < amount) {
System.out.println("Less balance;  waiting for deposit... ");
try {
wait();
            } catch (Exception e) {

            }
        }
this.amount -= amount;
System.out.println("withdraw completed... now balance is " + this.amount);
    }

synchronized void deposit(int amount) {
System.out.println("going to deposit... " + amount );
this.amount += amount;
System.out.println("deposit completed... now balance is " + this.amount);
notify();
    }

void printBalance() {
System.out.println("Current balance : " + this.amount);
    }


public static void main(String args[]) {
final Customer c = new Customer();
c.printBalance();

new Thread() {
public void run() {
c.withdraw(15000);
            }
        }.start();

new Thread() {
public void run() {
c.deposit(11000);
            }
        }.start();

    }
}

Current balance : 10000

going to withdraw...15000

Less balance;  waiting for deposit...

going to deposit... 11000

deposit completed... now balance is 21000

withdraw completed... now balance is 6000