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本题目：两个线程需要轮流打印两个数，涉及了线程间的通信及wait()和notify()的应用。

第一种方法

解题思路：用synchronized来锁住对象，wait和notify进行线程间的通信。

先创建一个待打印的类

//新建一个类，用于打印这个类class Num{
   	int i = 1;	// 标识	boolean flag = false; 	public Num() {
   			}}

再创建一个奇数线程

// 奇数线程class PrintOdd implements Runnable{
   	Num num;	public PrintOdd(Num num) {
   		this.num = num;	}		@Override	public void run() {
   		while(num.i<=100) {
   			// 锁住该对象			synchronized (num) {
   				// 判断当前线程是否执行				if(num.flag) {
   					try {
   						num.wait();					}catch(InterruptedException e) {
   						System.out.println(e.getMessage());					}				}else {
   					System.out.println(Thread.currentThread().getName()+num.i);					num.i++;					num.flag = true;					// 唤醒					num.notify();				}							}		}			}}

之后创建一个偶数线程

// 偶数线程class PrintEven implements Runnable{
   	Num num;	public PrintEven(Num num) {
   		this.num = num;	}	@Override	public void run() {
   		// TODO Auto-generated method stub		while(num.i<=100) {
   			// 锁住这个对象			synchronized (num) {
   				if(!num.flag) {
   					try {
   						num.wait();					}catch (InterruptedException e) {
   						// TODO: handle exception						System.out.print(e.getMessage());					}				}else {
   					System.out.println(Thread.currentThread().getName()+num.i);					num.i++;					num.flag = false;					num.notify();				}			}		}	}}

最后主函数中测试

public class Print_Odd_Even {
   		public static void main(String[] args) {
   		Num num = new Num();				PrintOdd printOdd = new PrintOdd(num);		PrintEven printEven = new PrintEven(num);				Thread thread1 = new Thread(printOdd);		Thread thread2 = new Thread(printEven);				thread1.setName("奇数线程:");		thread2.setName("偶数线程:");		thread1.start();		thread2.start();	}	}

第二种方法

用匿名内部类的方法，思路也是synchronized和wait和notify

package com.lcz.thread;import com.sun.org.apache.xalan.internal.xsltc.compiler.sym;// 多线程:两个线程轮流打印1-100// 解题思路：synchronized以及wait和notifyclass MyThread{
   	int num = 1;	// 方法	public void increase() {
   		while(num<=100) {
   			synchronized (this) {
   				notify();				System.out.println(Thread.currentThread().getName()+" "+(num++));				try {
   					wait();				}catch (InterruptedException e) {
   					System.out.print(e.getMessage());				}			}		}			}}public class Print_Odd_Even2 {
   		public static void main(String[] args) {
   		MyThread mythread = new MyThread();				new Thread(()-> {
   			mythread.increase();		}).start();				new Thread(()-> {
   			mythread.increase();		}).start();	}	}

第三种方式

上面的锁的方式是隐式锁synchronized，这里我们用显式锁reentrantlock以及condition信号量

package com.lcz.thread;import java.util.concurrent.locks.Condition;import java.util.concurrent.locks.ReentrantLock;// 多线程:两个线程轮流打印1-100// 解题思路：synchronized以及wait和notifyclass MyThread{
   	int num = 1;	ReentrantLock lock = new ReentrantLock();	Condition condition = lock.newCondition();		public void increase() {
   		while(num <= 100) {
   			try {
   				lock.lock();				condition.signal();				System.out.println(Thread.currentThread().getName() + " " + num++);				try {
   					condition.await();				} catch (InterruptedException e) {
   					e.printStackTrace();				} 			} finally {
   				lock.unlock();			}		}	}}public class Print_Odd_Even2 {
   		public static void main(String[] args) {
   		MyThread mythread = new MyThread();				new Thread(()-> {
   			mythread.increase();		}).start();				new Thread(()-> {
   			mythread.increase();		}).start();	}	}

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