要求描述
两个线程，其中一个线程打印奇数，另外一个线程打印偶数。两个线程交替打印，输入1,2,3，...，100
基本思路
利用通知等待机制，第一个线程打印后，然后唤醒第二个线程，并释放锁。第二个线程执行同样的操作
代码实现
package basicKnowledge.thread;
import java.util.concurrent.atomic.AtomicInteger;
/**
* @基本功能:线程交替打印输出奇偶
* @program:summary
* @author:peicc
* @create:2019-09-26 09:11:15
**/
public class ThreadPrint {
static Object object=new Object();
public static void main(String[] args) {
Thread thread1=new Thread(new Runnable() {
@Override
public void run() {
synchronized (object){
for (int i = 1; i <100 ; i+=2) {
System.out.println(Thread.currentThread().getName()+": "+i);
object.notify();//唤醒其他线程
try {
object.wait();
}
catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}
},"打印奇数线程");
Thread thread2=new Thread(new Runnable() {
@Override
public void run() {
synchronized (object){
for (int i = 2; i <=100 ; i+=2) {
System.out.println(Thread.currentThread().getName()+": "+i);
object.notify();//唤醒其他线程
try {
object.wait();
}
catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}
},"打印偶数线程");
thread1.start();
thread2.start();
}
}
输出结果（后面的省略）
打印奇数线程: 1
打印偶数线程: 2
打印奇数线程: 3
打印偶数线程: 4
打印奇数线程: 5
打印偶数线程: 6
打印奇数线程: 7
打印偶数线程: 8
打印奇数线程: 9
打印偶数线程: 10
上述方法基本解决了我们的需求，但是有个问题，很严重，那就是打印结束后打印偶数的线程再次进入了等待状态，整个程序无法终止。
代码升级版
package leetcode;
/**
* @基本功能:两个线程交替执行，一个输出偶数，一个输出奇数
* @program:summary
* @author:peicc
* @create:2019-07-29 12:56:49
**/
//线程执行完毕如何终止？
public class ThreadTurn {
static Object o=new Object();
static boolean flag=false;//标志位
public static void main(String[] args) {
ThreadTurn threadTurn=new ThreadTurn();
Thread oddThread=new Thread(new Runnable() {
@Override
public void run() {
synchronized (threadTurn){
for (int i = 1; i <100 ; ) {
if(!flag){
System.out.println("打印奇数线程"+i);
threadTurn.notify();//唤醒等待线程
flag=true;
i+=2;
}else{
try {
threadTurn.wait();
// Thread.sleep(100);
}
catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}
}
},"奇数线程");
Thread evenThread=new Thread(new Runnable() {
@Override
public void run() {
synchronized (threadTurn){
for (int i = 2; i <= 100; ) {
if(flag){
System.out.println("打印偶数线程"+i);
threadTurn.notify();//唤醒等待线程
flag=false;
i+=2;
}else{
try {
threadTurn.wait();
// Thread.sleep(100);
}
catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}
}
},"偶数线程");
evenThread.start();
oddThread.start();
}
}
补充练习
两个线程，其中一个线程打印数字，另外一个线程打印字母。两个线程交替打印，输入1,2,a,3,4,b,5,6,c
package basicKnowledge.thread;
/**
* @基本功能:两个线程交替执行，一个输出偶数，一个输出奇数
* @program:summary
* @author:peicc
* @create:2019-07-29 12:56:49
**/
//线程执行完毕如何终止？
public class ThreadPrint2 {
static Object o=new Object();
static boolean flag=true;//标志位
public static void main(String[] args) {
ThreadPrint2 threadTurn=new ThreadPrint2();
Thread oddThread=new Thread(new Runnable() {
@Override
public void run() {
synchronized (threadTurn){
int count=0;
for (int i = 1; i <=52 ; ) {
if(count<2){
System.out.println("打印数字线程"+i);
threadTurn.notify();//唤醒等待线程
count++;
i++;
}else{
try {
count=0;
threadTurn.wait();
// Thread.sleep(100);
}
catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}
}
},"奇数线程");
Thread evenThread=new Thread(new Runnable() {
@Override
public void run() {
synchronized (threadTurn){
for (int i = 0; i <26; ) {
if(flag){
System.out.println("打印字母线程"+(char)(i+'a'));
threadTurn.notify();//唤醒等待线程
flag=false;
i++;
}else{
try {
flag=true;
threadTurn.wait();
// Thread.sleep(100);
}
catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}
}
},"偶数线程");
oddThread.start();
evenThread.start();
}
}