第一种信号量的方式

package thread;

import java.util.concurrent.Semaphore;

public class PrintNumber {
    //打印偶数
    static Semaphore printEven = new Semaphore(1);
    //打印奇数
    static Semaphore printOdd = new Semaphore(0);

    public static void main(String[] args) throws InterruptedException {
        PrintEven p1 = new PrintEven();
        PrintOdd p2 = new PrintOdd();
        p1.start();
        p2.start();
        p1.join();
        p2.join();

    }

    static class PrintEven extends Thread {
        @Override
        public void run() {
            for (int i = 0; i <= 10; i += 2) {
                try {
                    printEven.acquire();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                System.out.println(currentThread().getName() + " " + i);
                printOdd.release();
            }
        }
    }

    static class PrintOdd extends Thread {
        @Override
        public void run() {
            for (int i = 1; i <= 10; i += 2) {
                try {
                    printOdd.acquire();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                System.out.println(currentThread().getName() + " " + i);
                printEven.release();
            }

        }
    }
}
\\output
Thread-0 0
Thread-1 1
Thread-0 2
Thread-1 3
Thread-0 4
Thread-1 5
Thread-0 6
Thread-1 7
Thread-0 8
Thread-1 9
Thread-0 10

第二种 Lock Condition的方式

package thread;

import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

public class PrintNumber1 {
    static Lock lock = new ReentrantLock();
    //打印奇数
    static Condition printOdd = lock.newCondition();
    //打印偶数
    static Condition printEven = lock.newCondition();
    //0的时候打印偶数，1的时候打印奇数
    static int point = 0;


    public static void main(String[] args) throws InterruptedException {
        PrintNumber.PrintEven p1 = new PrintNumber.PrintEven();
        PrintNumber.PrintOdd p2 = new PrintNumber.PrintOdd();
        p1.start();
        p2.start();
        p1.join();
        p2.join();

    }

    static class PrintEven extends Thread {
        @Override
        public void run() {
            for (int i = 0; i <= 10; i += 2) {
                lock.lock();
                try {
                    while (point != 0) {
                        printEven.await();
                    }
                    System.out.println(currentThread().getName() + " " + i);
                    point = 1;
                    printOdd.signalAll();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                } finally {
                    lock.unlock();
                }


            }
        }
    }

    static class PrintOdd extends Thread {
        @Override
        public void run() {
            for (int i = 1; i <= 10; i += 2) {
                lock.lock();
                try {
                    while (point != 1) {
                        printOdd.await();
                    }
                    System.out.println(currentThread().getName() + " " + i);
                    point = 0;
                    printEven.signalAll();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                } finally {
                    lock.unlock();
                }
            }

        }
    }
}