// Example 93 from page 69 of Java Precisely second edition (The MIT Press 2005)
// Author: Peter Sestoft (sestoft@itu.dk)


class Bank {
  private int account1 = 10, account2 = 20;
  synchronized public void transfer(int amount) {
    int new1 = account1 - amount;
    Util.pause(10);
    account1 = new1; account2 = account2 + amount;   
    System.out.println("Sum is " + (account1+account2));
} }

class Clerk extends Thread {
  private Bank bank;
  public Clerk(Bank bank) { this.bank = bank; }
  public void run() {
    for (;;) {                                  // Forever
      bank.transfer(Util.random(-10, 10));      //   transfer money
      Util.pause(200, 300);                     //   then take a break
} } }

class Example93 {
  public static void main(String[] args) {
    Bank bank = new Bank();
    new Clerk(bank).start(); new Clerk(bank).start();
} }