[问答题]
使用Java实现
/**
* 顺序打印-进阶版
*
* 有三个线程，分别只能打印A，B和C
* 要求按顺序打印ABC，打印10次
* 输出示例：
* ABC
* ABC
* ABC
* ......
*
* 解法：使用循环数组配合线程通信
*/
public class Demo {
// 要输出的信息数组
private static String[] INFO = {"A","B","C"};
// 数组下标
private static volatile int INDEX = 0;
// 打印次数
private static final int NUM = 10;
// 线程所包含的任务
static class Task implements Runnable{
private String info; //需要打印的字符串信息
public Task(String info) {
this.info = info;
}
@Override
public void run() {
//循环打印
for (int i = 0; i < NUM; i++) {
//获取同步锁
synchronized (Task.class){
//检查是否轮到当前线程
while(!info.equals(INFO[INDEX])){ //每次唤醒都需要判断是否满足条件
try {
//不满足条件则主动等待并释放锁
Task.class.wait();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
//输出字符串信息
System.out.print(info);
//若输出信息是最后一个时则换行
if(INDEX == INFO.length - 1){
System.out.println();
}
//轮到下一个线程打印
INDEX = (INDEX + 1) % INFO.length;
Task.class.notifyAll();
}
}
}
}
public static void main(String[] args) {
new Thread(new Task("A")).start();
new Thread(new Task("B")).start();
new Thread(new Task("C")).start();
}
}
发表于 2023-02-19 11:42:10
回复(0)
package concurrent; import java.util.concurrent.locks.LockSupport; public class LockSupportDemo2 { static Thread A,B,C; public static void main(String[] args) { A = new Thread(()->{ for (int i = 0; i < 10; i++) { LockSupport.park(); System.out.print("A"); LockSupport.unpark(B); } }); B = new Thread(()->{ for (int i = 0; i < 10; i++) { LockSupport.park(); System.out.print("B"); LockSupport.unpark(C); } }); C = new Thread(()->{ for (int i = 0; i < 10; i++) { LockSupport.unpark(A); LockSupport.park(); System.out.print("C"); } }); A.start(); B.start(); C.start(); } }
发表于 2021-02-23 15:56:50
回复(2)
自旋锁解法，不加同步块和JDK锁（线程启动部分没贴出来）
class Task3{
private volatile boolean firstDone;
private volatile boolean secondDone;
private volatile boolean thirdDone = true;
volatile int sum =0;
void first(){
while (true){
while (!thirdDone){
//等待第三个线程的完成
}
sum++;
System.out.println(Thread.currentThread().getName()+" : A 计数："+sum);
thirdDone=false;
firstDone=true;
if(sum==28)return;
}
}
void second(){
while (true){
while (!firstDone){
//等待一个线程完成
}
sum++;
System.out.println(Thread.currentThread().getName()+" : B 计数："+sum);
secondDone=true;
firstDone=false;
if(sum==29)return;
}
}
void third(){
while (true){
while (!secondDone){
//等待第二线程完成
}
sum++;
System.out.println(Thread.currentThread().getName()+" : C 计数："+sum);
System.out.println("===================================================");
secondDone=false;
thirdDone=true;
if(sum==30)return;
}
}
}
编辑于 2021-02-24 14:01:45
回复(0)
public void test() { for (int x = 1; x <= 10; x++) { CompletableFuture.runAsync(() -> { System.out.println("线程A" ); }).thenRunAsync(() -> { System.out.println("线程B"); }).thenRunAsync(() -> { System.out.println("线程C"); }); try { TimeUnit.SECONDS.sleep(1); }catch (Exception e) { e.printStackTrace(); } } }
发表于 2021-02-18 17:35:47
回复(0)
package real;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;
public class DiffPrint {
private volatile int num = 0;
private Lock lock = new ReentrantLock();
private Condition a = lock.newCondition(),
b = lock.newCondition(),
c = lock.newCondition();
public void printA() {
while (num < 30) {
lock.lock();
while (num > 0 && num % 3 != 0) {
try {
a.await();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
System.out.println("a");
num++;
b.signal();
lock.unlock();
}
}
public void printB() {
while (num < 30) {
lock.lock();
while (num % 3 != 1) {
try {
b.await();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
System.out.println("b");
num++;
c.signal();
lock.unlock();
}
}
public void printC() {
while (num < 30) {
lock.lock();
while (num % 3 != 2) {
try {
c.await();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
System.out.println("c");
num++;
a.signal();
lock.unlock();
}
}
public static void main(String[] args) {
DiffPrint dp = new DiffPrint();
new Thread(() -> {
dp.printA();
}).start();
new Thread(() -> {
dp.printB();
}).start();
new Thread(() -> {
dp.printC();
}).start();
}
}
发表于 2022-03-09 13:14:19
回复(0)
package com.lyr.common.demo.aqs;
import java.lang.reflect.Field;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.util.Map;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.ReentrantLock;
/**
* @Author lyr
* @create 2021/1/27 22:27
*/
public class SimpleLock {
public static void main(String[] args) throws Exception {
new Thread(()->{
synchronized (lock) {
while (modCount<30) {
if (A=='A') {
modCount++;
System.out.println(A);
A++;
}else{
lock.notifyAll();
try {
// if (modCount>=30) break;
lock.wait();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
lock.notifyAll();
}
}).start();
new Thread(()->{
synchronized (lock) {
while (modCount<30) {
if (A=='B'){
modCount++;
System.out.println( A);
A++;
}else{
try {
lock.notifyAll();
// if (modCount>=30) break;
lock.wait();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
lock.notifyAll();
}
}).start();
new Thread(()->{
synchronized (lock) {
while (modCount<30) {
if (A=='C') {
modCount++;
System.out.println( A );
A = 'A';
}else{
lock.notifyAll();
// if (modCount>=30) break;
try {
lock.wait();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
lock.notifyAll();
}
}).start();
}
volatile static char A = 'A';
volatile static Object lock = new Object();
volatile static int modCount = 0;
}
发表于 2021-01-28 17:10:05
回复(0)
@Data static class Test implements Runnable { private static Integer totalNum = 0; private static String[] order; private Integer printTimes; private String name; public Test(String name, Integer printTimes) { this.name = name; this.printTimes = printTimes; } @Override public void run() { int startNum = 1; while (startNum <= printTimes) { if (currentName(totalNum).equals(name)) { System.out.print(name); startNum++; totalNum++; try { Thread.sleep(5); } catch (InterruptedException e) { e.printStackTrace(); break; } } } } public String currentName(Integer totalNum) { return order[totalNum % order.length]; } } public static void main(String[] args) { Test.order = new String[]{"A", "B", "C"}; new Thread(new Test("A", 10)).start(); new Thread(new Test("B", 10)).start(); new Thread(new Test("C", 10)).start(); }
发表于 2021-01-28 11:36:41
回复(0)
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