1 Realize with wait and notify
public class NotifyFreeLock {
volatile List lists = new ArrayList<>();
public void add(Object o) {
lists.add(0);
}
public int size() {
return lists.size();
}
public static void main(String[] args) {
NotifyHoldingLock c = new NotifyHoldingLock();
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("The end of t2");
//Notify t1 to continue execution
lock.notify();
}
}, "t2").start();
try {
TimeUnit.SECONDS.sleep(1);
} catch (InterruptedException e) {
e.printStackTrace();
}
new Thread(() -> {
System.out.println("t1 start");
synchronized (lock) {
for (int i = 0; i <10; i++) {
c.add(new Object());
System.out.println("add " + i);
if (c.size() == 5) {
lock.notify();
//Release the lock and let t2 be executed
try {
lock.wait();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}
}, "t1").start();
}
}
2 Implemented with LockSupport
public class T_LockSupport2 {
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) {
T_LockSupport2 c = new T_LockSupport2();
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();
}
}
System.out.println("t2 结束");
}, "t2");
try {
TimeUnit.SECONDS.sleep(1);
} catch (InterruptedException e) {
e.printStackTrace();
}
t2 = new Thread(() -> {
LockSupport.park();
System.out.println("t2 结束");
LockSupport.unpark(t1);
}, "t2");
t2.start();
t1.start();
}
}
3 Realize with Semaphore
public class T_Semaphore {
// 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) {
T_Semaphore c = new T_Semaphore();
Semaphore s = new Semaphore(1);
t1 = new Thread(() -> {
try {
s.acquire();
for (int i = 0; i < 5; i++) {
c.add(new Object());
System.out.println("add " + i);
}
s.release();
} catch (InterruptedException e) {
e.printStackTrace();
}
t2.start();
try {
t2.join();
} catch (InterruptedException e) {
e.printStackTrace();
}
try {
s.acquire();
for (int i =5;i<10;i++){
System.out.println(i);
}
s.release();
} catch (InterruptedException e) {
e.printStackTrace();
}
},"t1");
t2 = new Thread(()->{
try {
s.acquire();
System.out.println("t2 结束");
s.release();
} catch (InterruptedException e) {
e.printStackTrace();
}
},"t2");
t1.start();
}
}
4 Implemented with two CountDownLatch
public class T_CountDownLatch {
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) {
T_CountDownLatch c = new T_CountDownLatch();
CountDownLatch latch = new CountDownLatch(1);
CountDownLatch latch2 = new CountDownLatch(1);
new Thread(() -> {
System.out.println("t2启动");
if (c.size() != 5) {
try {
latch.await();
latch2.countDown();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
System.out.println("t2 结束");
}, "t2").start();
try {
TimeUnit.SECONDS.sleep(1);
} catch (InterruptedException e) {
e.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 ){
latch.countDown();
try {
latch2.await();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
},"t1").start();
}
}