实现一个生产者，消费者

思路：用lock锁。定义一个类成员变量 max_value，min_value代表资源的最大，最小数量。

package org.app.common;import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;public class Resource {private int MAX_VALUE= 3;  private  int MIN_VALUE=0;private   int number = 0;private Lock lock = new ReentrantLock();private Condition condition = lock.newCondition();public void consume(){try {lock.lock();while(number <= MIN_VALUE){condition.await();}number--;System.out.println("【消费者】：消费了一个产品,【现仓储量为】:" + number);condition.signalAll();} catch (InterruptedException e) {e.printStackTrace();}finally {lock.unlock();}}public void produce(){try {lock.lock();while (number >MAX_VALUE) {condition.await();}number++;System.out.println("【生产者】：生产了一个产品\t【现仓储量为】:" + number);condition.signalAll();}catch (Exception e){}finally {lock.unlock();}}public static void main(String[] args) {Resource resouce = new Resource();new Thread(()->{for(int i=0;i<10;i++){resouce.produce();}}).start();//生产者//消费者new Thread(()->{for (int i=1;i<=5;i++){resouce.consume();}},String.valueOf("消费者")).start();}
}

线程交替打印问题

2个线程交替打印1-10

问题解决方法比较多。

private static volatile int num = 1;
private static Object lock = new Object();public static void main(String[] args) {Thread t1 = new Thread() {public void run() {while (num < 99) {if (num % 2 == 0) {synchronized (lock) {lock.notify();System.out.println("t1" + "_" + num);num++;try {lock.wait();} catch (InterruptedException e) {throw new RuntimeException(e);}}}}}};Thread t2 = new Thread() {public void run() {while (num < 99) {if (num % 2 == 1) {synchronized (lock) {lock.notify();System.out.println("t2" + "_" + num);num++;try {lock.wait();} catch (InterruptedException e) {throw new RuntimeException(e);}}}}}};t1.start();t2.start();

import java.util.*;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;public class Main2 {private int time;private int state;private Lock lock = new ReentrantLock();public Main2(int time){this.time = time;}public void print(String name,int targetNum){for(int i=0;i<time;){lock.lock();if (state % 3 == targetNum) {state++;i++;System.out.println(name);}lock.unlock();}}public static void main(String[] args) {Main2 main2 = new Main2(2);new Thread(()->{main2.print("B", 1);},"B").start();      new Thread(()->{main2.print("C", 2);},"C").start();new Thread(()->{main2.print("A", 0);},"A").start();}
}