多线程(三)
2019獨(dú)角獸企業(yè)重金招聘Python工程師標(biāo)準(zhǔn)>>>
package com.ninemax.application.multithread;public class FetchMoneyTest {public static void main(String[] args) {Bank bank = new Bank();Thread t1 = new MoneyThread(bank);// 從銀行取錢(qián)Thread t2 = new MoneyThread(bank);// 從取款機(jī)取錢(qián)t1.start();t2.start();}}class Bank {private int money = 1000;public synchronized int getMoney(int number) {if (number < 0) {return -1;} else if (number > money) {return -2;} else if (money < 0) {return -3;} else {try {Thread.sleep(1000);} catch (InterruptedException e) {e.printStackTrace();}money -= number;System.out.println("Left Money: " + money);return number;}}}class MoneyThread extends Thread {private Bank bank;public MoneyThread(Bank bank) {this.bank = bank;}@Overridepublic void run() {System.out.println(bank.getMoney(800));} }運(yùn)行結(jié)果:
Left Money: 200 800 -2如果方法沒(méi)有加synchronized關(guān)鍵字,運(yùn)行結(jié)果:
Left Money: -600 800 Left Money: -600 800上面結(jié)果是因?yàn)樵诘谝粋€(gè)線程sleep的時(shí)候,第二個(gè)線程也訪問(wèn)到了相同的資源,所以需要在方法上鎖,才能同步.
轉(zhuǎn)載于:https://my.oschina.net/Tsher2015/blog/682749
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