CachedThreadPool.java

package ch21concurrent;//: concurrency/CachedThreadPool.java

import java.util.concurrent.*;

/**
 * 使用Executor管理线程
 * 优先考虑CachedThreadPool
 * 其次是FixedThreadPool
 * 如果你希望有一个长期存活任务的话，用SingleThreadExecutor
 */
public class CachedThreadPool {
    public static void threadPool() {
        ExecutorService exec = Executors.newCachedThreadPool();
        for (int i = 0; i < 5; i++)
            exec.execute(new LiftOff());
        exec.shutdown();
    }
} /*
 * Output: (Sample) #0(9), #0(8), #1(9), #2(9), #3(9), #4(9), #0(7), #1(8),
 * #2(8), #3(8), #4(8), #0(6), #1(7), #2(7), #3(7), #4(7), #0(5), #1(6), #2(6),
 * #3(6), #4(6), #0(4), #1(5), #2(5), #3(5), #4(5), #0(3), #1(4), #2(4), #3(4),
 * #4(4), #0(2), #1(3), #2(3), #3(3), #4(3), #0(1), #1(2), #2(2), #3(2), #4(2),
 * #0(Liftoff!), #1(1), #2(1), #3(1), #4(1), #1(Liftoff!), #2(Liftoff!),
 * #3(Liftoff!), #4(Liftoff!),
 */// :~

class LiftOff implements Runnable {
    protected int countDown = 10; // Default
    private static int taskCount = 0;
    private final int id = taskCount++;

    public LiftOff() {
    }

    public LiftOff(int countDown) {
        this.countDown = countDown;
    }

    public String status() {
        return "#" + id + "(" + (countDown > 0 ? countDown : "Liftoff!") + "), ";
    }

    public void run() {
        while (countDown-- > 0) {
            System.out.print(status());
            Thread.yield();
        }
    }
} // /:~