三个线程分别打印A，B，C，要求这三个线程一起运行，打印n次，输出形如“ABCABCABC….”的字符串。
Semaphore
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| package concurrent;
import java.util.concurrent.Semaphore;
public class PrintABCBySemaphore {
private int times;
private Semaphore semaphoreA =new Semaphore(1);
private Semaphore semaphoreB =new Semaphore(0);
private Semaphore semaphoreC =new Semaphore(0);
public PrintABCBySemaphore(int times) {
this.times=times;
}
public static void main(String[] args) {
PrintABCBySemaphore printABCBySemaphore =new PrintABCBySemaphore(10);
new Thread(printABCBySemaphore::printA).start();
new Thread(printABCBySemaphore::printB).start();
new Thread(printABCBySemaphore::printC).start();
}
public void printA() {
print("A",semaphoreA,semaphoreB);
}
public void printB() {
print("B",semaphoreB,semaphoreC);
}
public void printC() {
print("C",semaphoreC,semaphoreA);
}
public void print(String name,Semaphore current,Semaphore next) {
for(int i=0;i<times;i++) {
try {
current.acquire();
} catch (InterruptedException e) {
e.printStackTrace();
}
System.out.println(Thread.currentThread().getName() +":" + i+ " :" + name);
next.release();
}
}
}
|
Lock
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| package concurrent;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;
public class PrintABCByLock {
private int times;
private int state;
private Lock lock =new ReentrantLock();
public PrintABCByLock(int times) {
this.times=times;
}
public static void main(String[] args) {
PrintABCByLock printABC =new PrintABCByLock(10);
new Thread(printABC::printA).start();
new Thread(printABC::printB).start();
new Thread(printABC::printC).start();
}
public void printA() {
print("A",0);
}
public void printB() {
print("B",1);
}
public void printC() {
print("C",2);
}
public void print(String name,int stateNow) {
for (int i = 0; i < times;) {
lock.lock();
if(stateNow == state % 3) {
state++;
i++;
System.out.println(Thread.currentThread().getName()
+ ":i=" + i + ":stateNow="+stateNow
+ ":" +name);
}
lock.unlock();
}
}
}
|
Condition
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| package concurrent;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;
public class PrintABCByLockCondition {
public static void main(String[] args) {
final Business business = new Business();
new Thread(new Runnable() {
@Override
public void run() {
for (int i = 0; i < 10; i++) {
business.sub2("B");
}
}
}).start();
new Thread(new Runnable() {
@Override
public void run() {
for (int i = 0; i < 10; i++) {
business.sub3("C");
}
}
}).start();
for (int i = 0; i < 10; i++) {
business.sub1("A");
}
}
static class Business {
private int flag = 1;
Lock lock = new ReentrantLock();
Condition condition1 = lock.newCondition();
Condition condition2 = lock.newCondition();
Condition condition3 = lock.newCondition();
public void sub1(String s) {
lock.lock();
try{
while(flag != 1) {
condition1.await();
}
System.out.println("A线程输出" + s);
flag = 2;
condition2.signal();
}catch (Exception e) {
e.printStackTrace();
} finally {
lock.unlock();
}
}
public void sub2(String s) {
lock.lock();
try{
while(flag != 2) {
condition2.await();
}
System.out.println("B线程输出" + s);
flag = 3;
condition3.signal();
}catch (Exception e) {
e.printStackTrace();
} finally {
lock.unlock();
}
}
public void sub3(String s) {
lock.lock();
try{
while(flag != 3) {
condition3.await();
}
System.out.println("C线程输出" + s);
flag = 1;
condition1.signal();
}catch (Exception e) {
e.printStackTrace();
} finally {
lock.unlock();
}
}
}
}
|
参考
并发编程】如果让你用三个线程循环打印ABC，你有几种写法？
