通过简单的练习题复习之前学习的关于多线程的知识。后期一直补充。
一、线程监控 1、实现一个容器，提供两个方法，add，size方法。 写两个线程，线程1添加10个元素到容器中，线程2实现监控元素的个数，当个数到5个时，线程2给出提示并结束
package com.zcm.juc;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.TimeUnit;
public class T04_NotifyFreeLock {
//添加volatile，使t2能够得到通知,其实没什么用
volatile List lists = new ArrayList();
public void add(Object o) {
lists.add(o);
}
public int size() {
return lists.size();
}
public static void main(String[] args) {
T04_NotifyFreeLock c = new T04_NotifyFreeLock();
final Object lock = new Object();
new Thread(() -> {
synchronized(lock) {
System.out.println("t2启动");
if(c.size() != 5) {
try {
lock.wait();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
System.out.println("t2 结束");
//通知t1继续执行
lock.notify();
}
}, "t2").start();
try {
TimeUnit.SECONDS.sleep(1);
} catch (InterruptedException e1) {
e1.printStackTrace();
}
new Thread(() -> {
System.out.println("t1启动");
synchronized(lock) {
for(int i=0; i<10; i++) {
c.add(new Object());
System.out.println("add " + i);
if(c.size() == 5) {
lock.notify();
//释放锁，让t2得以执行,如果不加这个的话会发现t2 结束可能不会在add 5之前
try {
lock.wait();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
try {
TimeUnit.SECONDS.sleep(1);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}, "t1").start();
}
}
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package com.zcm.juc;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.locks.LockSupport;
//TODO park unpark
public class T06_LockSupport {
// 添加volatile，使t2能够得到通知
volatile List lists = new ArrayList();
public void add(Object o) {
lists.add(o);
}
public int size() {
return lists.size();
}
public static void main(String[] args) {
T06_LockSupport c = new T06_LockSupport();
CountDownLatch latch = new CountDownLatch(1);
Thread t2 = new Thread(() -> {
System.out.println("t2启动");
if (c.size() != 5) {
LockSupport.park();
}
System.out.println("t2 结束");
}, "t2");
t2.start();
try {
TimeUnit.SECONDS.sleep(1);
} catch (InterruptedException e1) {
e1.printStackTrace();
}
new Thread(() -> {
System.out.println("t1启动");
for (int i = 0; i < 10; i++) {
c.add(new Object());
System.out.println("add " + i);
if (c.size() == 5) {
LockSupport.unpark(t2);
}
}
}, "t1").start();
}
}
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package com.zcm;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.locks.LockSupport;
//TODO park unpark
public class T07_LockSupport_WithoutSleep {
// 添加volatile，使t2能够得到通知
volatile List lists = new ArrayList();
public void add(Object o) {
lists.add(o);
}
public int size() {
return lists.size();
}
static Thread t1 = null, t2 = null;
public static void main(String[] args) {
T07_LockSupport_WithoutSleep c = new T07_LockSupport_WithoutSleep();
t1 = new Thread(() -> {
System.out.println("t1启动");
for (int i = 0; i < 10; i++) {
c.add(new Object());
System.out.println("add " + i);
if (c.size() == 5) {
LockSupport.unpark(t2);
LockSupport.park();
}
}
}, "t1");
t2 = new Thread(() -> {
//System.out.println("t2启动");
//if (c.size() != 5) {
LockSupport.park();
//}
System.out.println("t2 结束");
LockSupport.unpark(t1);
}, "t2");
t2.start();
t1.start();
}
}
