满足一下条件
- 定义一个容器 提供添加元素和获取元素数量的 方法
- 启动两个线程 第一个添加元素，第二个获取元素，当第二个获取的元素的长度为5时 结束这个线程
1，使用 volatile
public class Test {
public static void main(String[] args) {
Container container = new Container();
new Thread(new Runnable() {
@Override
public void run() {
for (int i = 0; i < 10; i++) {
container.add(new Object());
System.out.println("add Object - "+ i);
try {
TimeUnit.SECONDS.sleep(1);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}).start();
new Thread(new Runnable() {
@Override
public void run() {
while(true) {
if(container.size()==5) {
System.out.println("t2 size() : 5");
break;
}
}
}
}).start();
}
}
class Container {
volatile List<Object> container = new ArrayList<Object>();
public void add(Object o) {
container.add(o);
}
public int size() {
return container.size();
}
}
2 ，使用CountDownLatch
public class Test {
public static void main(String[] args) {
Container container = new Container();
CountDownLatch latch = new CountDownLatch(1);
new Thread(new Runnable() {
@Override
public void run() {
for (int i = 0; i < 10; i++) {
container.add(new Object());
System.out.println("add Object() - "+ i);
if(container.size()==5) {
latch.countDown(); //减去一个门闩
}
try {
TimeUnit.SECONDS.sleep(1);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}).start();
new Thread(new Runnable() {
@Override
public void run() {
if(container.size()!=5) {
try {
latch.await(); //等待门闩开放
} catch (InterruptedException e) {
e.printStackTrace();
}
}
System.out.println("t2 size() 5");
}
}).start();
}
}
class Container {
List<Object> container = new ArrayList<Object>();
public void add(Object o) {
container.add(o);
}
public int size() {
return container.size();
}
}
3,wait() 和notifyAll()
public class Test {
public static void main(String[] args) {
Container container = new Container();
Object lock = new Object();
new Thread(new Runnable() {
@Override
public void run() {
synchronized (lock) {
for (int i = 0; i < 10; i++) {
container.add(new Object());
System.out.println("add Object - " + i);
try {
TimeUnit.SECONDS.sleep(1);
} catch (InterruptedException e1) {
e1.printStackTrace();
}
if(container.size()==5) {
try {
lock.wait();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
lock.notifyAll();
}
}
}
}).start();
new Thread(new Runnable() {
@Override
public void run() {
synchronized (lock) {
if(container.size()!=5) {
try {
lock.wait();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
System.out.println("t2 size() 5");
lock.notifyAll();
}
}
}).start();
}
}
class Container {
List<Object> container = new ArrayList<Object>();
public void add(Object o) {
container.add(o);
}
public int size() {
return container.size();
}
}
