4月17日，TestCommunicate，每日20行。

class Account{    volatile private int value;    void put(int i){        value = value + i;        System.out.println("存入" + i + " 账上金额为：" + value);    }    int get(int i){        if(value > i)            value = value - i;        else{            i = value;            value = 0;        }        System.out.println("取走" + i + " 账上金额为：" + value);        return i;    }}class Save implements Runnable{    private Account a1;    public Save(Account a1){        this.a1 = a1;    }    public void run(){        while(true){            a1.put(100);        }    }}class Fetch implements Runnable{    private Account a1;    public Fetch(Account a1){        this.a1 = a1;    }    public void run(){        while(true){            a1.get(100);        }    }}public class TestCommunicate {    public static void main(String[] args) {        Account a1 = new Account();        new Thread(new Save(a1)).start();        new Thread(new Fetch(a1)).start();    }}