線程通訊：一個線程完成了自己的任務時，要通知另外一個線程去完成另外一個任務

public class Demo1 {public static void main(String [] args){Product p = new Product ();Producer producer = new Producer (p);Customer customer = new Customer (p);producer.start ();customer.start ();}} class Product{double price;String name; } class Producer extends Thread{Product p;public Producer(Product p){this.p = p;}public void run(){int i =0;while(true){if(i%2 ==0){p.name="蘋果";try {Thread.sleep (10);} catch (InterruptedException e) {e.printStackTrace ();}p.price=6.5;}else{p.name="香蕉";p.price=2.0;}System.out.println ("生產者生產了："+p.name+" 價格是："+p.price);i++;}} }class Customer extends Thread{Product p;public Customer(Product product){this.p = product;}public void run(){while(true){System.out.println ("消費者消費了："+p.name+" 價格是："+p.price);}}} 消費者消費了：蘋果 價格是：2.0 消費者消費了：蘋果 價格是：2.0 消費者消費了：蘋果 價格是：2.0 消費者消費了：蘋果 價格是：2.0 消費者消費了：蘋果 價格是：2.0

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解決價格錯亂問題-加synchronized關鍵字

public class Demo {public static void main(String [] args){Product p = new Product ();Producer producer = new Producer (p);Customer customer = new Customer (p);producer.start ();customer.start ();}} class Product{double price;String name; } class Producer extends Thread{Product p;public Producer(Product p){this.p = p;}public void run(){int i =0;while(true){synchronized (p) {if (i % 2 == 0) {p.name = "蘋果";try {Thread.sleep (10);} catch (InterruptedException e) {e.printStackTrace ();}p.price = 6.5;} else {p.name = "香蕉";p.price = 2.0;}System.out.println ("生產者生產了：" + p.name + " 價格是：" + p.price);i++;}}} }class Customer extends Thread{Product p;public Customer(Product product){this.p = product;}public void run(){while(true) {synchronized (p) {System.out.println ("消費者消費了：" + p.name + " 價格是：" + p.price);}}}}

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要求：

生產者生產完一個產品之后就要等待消費者去消費，然后在生產，

消費者消費完一個產品之后就要等待生產者去生產

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wait() 等待 如果線程執行了wait方法那么該線程會進入等待的狀態，等待狀態下的線程必須調用notify 方法才能喚醒

notify（）喚醒 喚醒等待的線程

wait與notify要注意的事項

1、wait 方法與notify 方法是屬于object對象的

2、wait 方法與notify方法必須要在同步代碼塊或者是同步函數中才能使用

3、wait方法與notify方法必須要有鎖對象調用。

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public class SaleTicket {public static void main(String [] args){Product p = new Product ();Producer producer = new Producer (p);Customer customer = new Customer (p);producer.start ();customer.start ();}} class Product{double price;String name;boolean flag = false;//產品生產完畢的標志，默認是沒有生產完畢的 } class Producer extends Thread{Product p;public Producer(Product p){this.p = p;}public void run(){int i =0;while(true){synchronized (p) {if(p.flag ==false) {if (i % 2 == 0) {p.name = "蘋果";try {Thread.sleep (10);} catch (InterruptedException e) {e.printStackTrace ();}p.price = 6.5;} else {p.name = "香蕉";p.price = 2.0;}System.out.println ("生產者生產了：" + p.name + " 價格是：" + p.price);i++;p.flag=true;p.notify ();//喚醒消費者去消費}else{//已經生產完畢，等待消費者先去消費try {p.wait ();} catch (InterruptedException e) {e.printStackTrace ();}}}}} }class Customer extends Thread{Product p;public Customer(Product product){this.p = product;}public void run(){while(true) {synchronized (p) {if(p.flag==true) {//產品已經生產完畢System.out.println ("消費者消費了：" + p.name + " 價格是：" + p.price);p.flag = false;p.notify ();//喚醒生產者去生產}else{//產品還沒有生產，應該等待生產者先去生產try {p.wait ();//消費者也等待了。。} catch (InterruptedException e) {e.printStackTrace ();}}}}}} 生產者生產了：蘋果 價格是：6.5 消費者消費了：蘋果 價格是：6.5 生產者生產了：香蕉 價格是：2.0 消費者消費了：香蕉 價格是：2.0

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轉載于:https://www.cnblogs.com/zhou-test/p/9879905.html

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