單線程是安全的，因?yàn)榫€程只有一個，不存在多個線程搶奪同一個資源
代碼例子：
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public class SingleThread { int num=10; public void add(){ while(num<13){ num++; try{ Thread.sleep(1000); } catch(Exception e){ System.out.println("中斷"); } System.out.println(num); } } public static void main(String[] args){ Thread thread = Thread.currentThread(); //獲取當(dāng)前運(yùn)行的線程對象 thread.setName("單線程"); //線程重命名 System.out.println(thread.getName()+"正在運(yùn)行"); SingleThread st=new SingleThread(); st.add(); }} |
多線程安全，synchronized同步代碼塊
synchronized(對象){}; //同步代碼塊
synchronized 返回值 方法名(){}; //同步方法
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class One { int num=10; public void add(){ synchronized(this){ //同步代碼塊,同步方法也可以實(shí)現(xiàn)效果synchronized void add(){}; num++; try { Thread.sleep(1000); } catch (InterruptedException e) { System.out.println("中斷"); } System.out.println(num); } } } class Two implements Runnable{ One one = new One(); @Override public void run() { one.add(); //調(diào)用add方法 } } public class Synch{ public static void main(String[] args) { Two two = new Two(); Thread t1 = new Thread(two); //創(chuàng)建三個子線程 Thread t2 = new Thread(two); Thread t3 = new Thread(two); t1.start(); t2.start(); t3.start(); }} |
注意：觀察去除synchronized關(guān)鍵字的運(yùn)行結(jié)果區(qū)別！
正常運(yùn)行結(jié)果：
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原文鏈接：https://www.idaobin.com/archives/839.html
