同步函数

class Bank {    private int sum;    public synchronized void add(int n) {  //与同步代码块类似，只需要在函数声明中加入synchronized修饰。        sum = sum + n;        try {            Thread.sleep(10);        } catch (Exception e) {}        System.out.println("sum=" + sum);    }}class Cus implements Runnable {    private Bank b = new Bank();    public void run() {        for (int x = 0; x < 3; x++) {            b.add(100);        }    }}class BankDemo {    public static void main(String[] args) {        Cus c = new Cus();        Thread t1 = new Thread(c);        Thread t2 = new Thread(c);        t1.start();        t2.start();    }}