编写一个程序，开启 3 个线程，这三个线程的 ID 分别为A、B、C，每个线程将自己的 ID 在屏幕上打印 10 遍，要求输出的结果必须按顺序显示。如：ABCABCABC…… 依次递归？
package com.company; import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock; /*
* 编写一个程序，开启 3 个线程，这三个线程的 ID 分别为 A、B、C，每个线程将自己的 ID 在屏幕上打印 10 遍，要求输出的结果必须按顺序显示。
* 如：ABCABCABC…… 依次递归
*/
public class TestABCAlternate { public static void main(String[] args) {
AlternateDemo ad = new AlternateDemo(); new Thread(() -> { for (int i = 1; i <= 10; i++) {
ad.loopA(i);
} }, "A").start(); new Thread(() -> { for (int i = 1; i <= 10; i++) {
ad.loopB(i);
} }, "B").start(); new Thread(() -> { for (int i = 1; i <= 10; i++) {
ad.loopC(i); } }, "C").start();
} } class AlternateDemo { private int number = 1; //当前正在执行线程的标记 private Lock lock = new ReentrantLock();
private Condition condition1 = lock.newCondition();
private Condition condition2 = lock.newCondition();
private Condition condition3 = lock.newCondition(); /**
* @param totalLoop : 循环第几轮
*/
void loopA(int totalLoop) {
lock.lock(); try {
//1. 判断
if (number != 1) {
condition1.await();
} //2. 打印
for (int i = 1; i <= 1; i++) {
System.out.println(Thread.currentThread().getName() + "\t" + i + "\t" + totalLoop);
} //3. 唤醒
number = 2;
condition2.signal();
} catch (Exception e) {
e.printStackTrace();
} finally {
lock.unlock();
}
} void loopB(int totalLoop) {
lock.lock(); try {
//1. 判断
if (number != 2) {
condition2.await();
} //2. 打印
for (int i = 1; i <= 1; i++) {
System.out.println(Thread.currentThread().getName() + "\t" + i + "\t" + totalLoop);
} //3. 唤醒
number = 3;
condition3.signal();
} catch (Exception e) {
e.printStackTrace();
} finally {
lock.unlock();
}
} void loopC(int totalLoop) {
lock.lock(); try {
//1. 判断
if (number != 3) {
condition3.await();
} //2. 打印
for (int i = 1; i <= 1; i++) {
System.out.println(Thread.currentThread().getName() + "\t" + i + "\t" + totalLoop);
}
System.out.println("------------------");
//3. 唤醒
number = 1;
condition1.signal();
} catch (Exception e) {
e.printStackTrace();
} finally {
lock.unlock();
}
} }
上面有一部分使用java1.8新特性写的，看下结果：
A 1 1
B 1 1
C 1 1
------------------
A 1 2
B 1 2
C 1 2
------------------
A 1 3
B 1 3
C 1 3
------------------
A 1 4
B 1 4
C 1 4
------------------
A 1 5
B 1 5
C 1 5
------------------
A 1 6
B 1 6
C 1 6
------------------
A 1 7
B 1 7
C 1 7
------------------
A 1 8
B 1 8
C 1 8
------------------
A 1 9
B 1 9
C 1 9
------------------
A 1 10
B 1 10
C 1 10
------------------