synchronized与 lock
区别
1)Lock不是Java语言内置的,synchronized是Java语言的关键字。Lock是一个接口,通过这个接口的实现类可以实现同步访问;
2)采用synchronized不需要手动释放锁,当synchronized方法或者synchronized代码块执行完之后,系统会自动让线程释放对锁的占用;而Lock则必须要用户去手动释放锁,如果没有主动释放锁,就有可能导致出现死锁现象。
使用synchronized同步交替打印-Runnable
package ThreadTest;
/**
* @author: Hongyuan Bai
* @create: 2018-12-27 14:13:39
* @description: 实现ruannable接口方式创建多线程
*/
public class Thread1 implements Runnable{
int sum = 200;
@Override
public void run() {
synchronized (this) {
while (sum > 0) {
try {
this.notify();
System.out.println(sum-- + Thread.currentThread().getName());
this.wait();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}
}
使用synchronized同步交替打印-Thread类
package ThreadTest;
/**
* @author: Hongyuan Bai
* @create: 2018-12-28 09:50:44
* @description: 继承Thread类方式创建多线程
*/
public class Thread2 extends Thread{
static int sum = 200;
Object obj;
public Thread2() {
}
public Thread2(Object obj) {
this.obj = obj;
}
@Override
public void run() {
synchronized (obj) {
while (sum > 0) {
try {
obj.notify();
System.out.println(sum-- + Thread.currentThread().getName());
obj.wait();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}
}
Lock实现同步
package ThreadTest;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;
/**
* @author: Hongyuan Bai
* @create: 2018-12-28 10:54:42
* @description: Lock实现同步
*/
public class Thread3 implements Runnable{
int sum = 200;
Lock lock = new ReentrantLock();
@Override
public void run() {
lock.lock();
try {
while (sum > 0) {
System.out.println(sum-- + Thread.currentThread().getName());
}
} finally {
lock.unlock();
}
}
}