解决线程安全的方式

1. 同步代码块

package cn.itcast.day_05.test_02;

public class RunnableImpl implements Runnable{

    private int tickets = 100;

    //创建对象
    Object obj = new Object();

    //设置线程任务
    @Override
    public void run() {
        //票存在，卖票
        while (true){
            synchronized (obj){  //同步代码块
                if (tickets > 0){
                    //提高安全性
                    try {
                        Thread.sleep(1000);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                    System.out.println(Thread.currentThread().getName()+"正在卖第"+tickets+"张票");
                    tickets--;
                }
            }
        }
    }
}

2. 同步方法

package cn.itcast.day_05.test_02;

public class RunnableImpl2 implements Runnable{

    private int tickets = 100;

    @Override
    public void run() {
        while (true){
            payTickets();
        }
    }

    //静态同步方法
    public synchronized void payTickets(){
        if (tickets > 0){
            try {
                Thread.sleep(1000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            System.out.println(Thread.currentThread().getName()+"正在卖第"+tickets+"张票");
            tickets--;
        }
    }
}

3. 静态同步方法

package cn.itcast.day_05.test_02;

public class RunnableImpl2 implements Runnable{

    private static int tickets = 100;

    @Override
    public void run() {
        while (true){
            payTickets();
        }
    }

    //静态同步方法
    public static synchronized void payTickets(){
        if (tickets > 0){
            try {
                Thread.sleep(1000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            System.out.println(Thread.currentThread().getName()+"正在卖第"+tickets+"张票");
            tickets--;
        }
    }
}

 4. Lock锁

package cn.itcast.day_05.test_02;

import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

public class RunnableImpl3 implements Runnable{

    private int tickets = 100;

    //创建ReentrantLock对象
    Lock i = new ReentrantLock();

    @Override
    public void run() {
        while (true){

            //加锁
            i.lock();

            if (tickets > 0){
                try {
                    Thread.sleep(1000);
                    System.out.println(Thread.currentThread().getName()+"正在卖第"+tickets+"张票");
                    tickets--;
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }finally {   //无论程序是否异常，都会释放锁
                    //解锁
                    i.unlock();
                }
            }
        }
    }
}