使用 2 个线程打印偶数和奇数
您好，我正在尝试使用名为 EvenThread 和 OddThread 的两个线程打印偶数和奇数，有时我得到正确的结果，有时却没有，有人可以帮助我吗？
package com.java8;
public class EvenOddExample {
public static synchronized void print(int i,String name){
System.out.println(i+"--->"+name);
}
public static void main(String[] args) throws InterruptedException {
EvenThread e= new EvenThread();
e.start();
OddThread o=new OddThread();
o.start();
}
public static class EvenThread extends Thread{
public void run() {
for(int i=0;i<10;i++){
if(i%2==0){
print(i,"Even");
}else{
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}
}
public static class OddThread extends Thread{
@Override
public void run() {
for(int i=1;i<10;i++){
if(i%2!=0){
print(i,"Odd");
}else{
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}
}
}
蛊毒传说3回答
-
四季花海
您需要两个线程之间的一些信号。放置synchronized方法print只是保证一次只有一个线程可以进入该方法。可以使用您的线程Object.wait()和方法。Object.notify{All}()实际上这是某种Sender-Receiver Synchronization Problem。我调整了您的代码。另外我使用了ExecutorServiceandCallable而不是 extending Thread，这是不好的做法：import java.util.concurrent.Callable;import java.util.concurrent.ExecutorService;import java.util.concurrent.Executors;public class EvenOddExample { private static boolean evensTurn = true; private static Object monitor = new Object(); public static void print(int i, String name) { System.out.println(i + "--->" + name); } public static void main(String[] args) throws InterruptedException { final ExecutorService executorService = Executors.newFixedThreadPool(2); executorService.submit(new EvenCallable()); executorService.submit(new OddCallable()); executorService.shutdown(); } public static class EvenCallable implements Callable<Void> { @Override public Void call() throws InterruptedException { for (int i = 0; i < 10; i++) { if (i % 2 == 0) { synchronized (monitor) { while (!evensTurn) { // not your turn? monitor.wait(); // wait for monitor in a loop to handle spurious wakeups } print(i, "Even"); evensTurn = false; // next odd needs to run monitor.notifyAll(); // wakeup the odd thread } } else { Thread.sleep(1000); } } return null; } } public static class OddCallable implements Callable<Void> { @Override public Void call() throws InterruptedException { for (int i = 1; i < 10; i++) { if (i % 2 != 0) { synchronized (monitor) { while (evensTurn) { monitor.wait(); } print(i, "Odd"); evensTurn = true; monitor.notifyAll(); } } else { Thread.sleep(1000); } } return null; } }} -
慕斯王
synchronized 用于锁定另一个线程的访问，当被锁定的对象空闲时，它不保证下一个调用哪个线程。您可以使用信号量进行线程间通信： private static Semaphore[] semaphores = {new Semaphore(0), new Semaphore(1)}; static void print(int i, String name) { try { semaphores[(i + 1) % 2].acquire(); } catch (InterruptedException e) { Thread.currentThread().interrupt(); } System.out.println(i + "--->" + name); semaphores[i % 2].release(); } -
holdtom
public class EvenOddPrinter { static boolean flag = true; public static void main(String[] args) { class Odd implements Runnable { @Override public void run() { for (int i = 1; i <= 10;) { if (EvenOddPrinter.flag) { System.out.println(i + "--->odd"); i += 2; EvenOddPrinter.flag = !EvenOddPrinter.flag; } } } } class Even implements Runnable { @Override public void run() { for (int i = 2; i <= 10;) { if (!EvenOddPrinter.flag) { System.out.println(i + "---->even"); i += 2; EvenOddPrinter.flag = !EvenOddPrinter.flag; } } } } Runnable odd = new Even(); Runnable even = new Odd(); Thread t1 = new Thread(odd, "Odd"); Thread t2 = new Thread(even, "Even"); t1.start(); t2.start(); }}
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Java