【发布时间】：2015-06-09 15:11:02
【问题描述】：
我正在尝试使用三个线程打印从 1 到 10 的数字。线程 1 打印 1，2 打印 2，3 打印 3，线程 1 再次打印 4，依此类推。
我创建了一个共享打印机资源来帮助这些线程打印数字。但我很困惑，我怎样才能让所有线程都看到这个数字。
问题是每个线程都看到自己的数字副本，而我需要所有线程共享相同的数字。
我正在尝试创建此示例以用于学习目的。我在 SO 上看到了其他有同样问题的页面，但我无法理解这个概念。
感谢任何帮助。
这个例子与我所做的有什么不同？ Printing Even and Odd using two Threads in Java
public class PrintAlternateNumber {
public static void main(String args[]) {
SharedPrinter printer = new SharedPrinter();
Thread t1 = new Thread(new myRunnable2(printer,10,1),"1");
Thread t2 = new Thread(new myRunnable2(printer,10,2),"2");
Thread t3 = new Thread(new myRunnable2(printer,10,3),"3");
t1.start();
t2.start();
t3.start();
}
}
class myRunnable2 implements Runnable {
int max;
SharedPrinter printer;
int threadNumber;
int number=1;
myRunnable2(SharedPrinter printer,int max,int threadNumber) {
this.max=max;
this.printer=printer;
this.threadNumber=threadNumber;
}
@Override
public void run() {
System.out.println(" The thread that just entered run "+ Thread.currentThread().getName());
for(int i =1;i<max;i++){
try {
printer.print(i,threadNumber);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}
class SharedPrinter {
boolean canPrintFlag=false;
public synchronized void print(int number,int threadNumber) throws InterruptedException{
if(number%3==threadNumber) {
canPrintFlag=true;
}
while(!canPrintFlag)
{
System.out.println(Thread.currentThread().getName() + " is waiting as it cannot print " + number);
wait();
}
System.out.println(Thread.currentThread().getName()+" printed "+number);
canPrintFlag=false;
notifyAll();
}
}
//output
//The thread that just entered run 2
// The thread that just entered run 3
//The thread that just entered run 1
//3 is waiting as it cannot print 1
//1 printed 1
//1 is waiting as it cannot print 2
//3 is waiting as it cannot print 1
//2 is waiting as it cannot print 1
技术二
它仍然不完整，但我很接近
输出
0由0印刷 2印刷者2 1印刷者1
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;
class AlternateNumber {
public static void main(String args[]) {
printerHell ph = new printerHell();
BlockingQueue<Integer> queue = new ArrayBlockingQueue<Integer>(10);
for(int i=0;i<10;i++)
{
queue.add(i);
}
Thread t1 = new Thread(new myRunnableHell(queue,0,ph),"0");
Thread t2 = new Thread(new myRunnableHell(queue,1,ph),"1");
Thread t3 = new Thread(new myRunnableHell(queue,2,ph),"2");
t1.start();
t2.start();
t3.start();
}
}
class myRunnableHell implements Runnable {
BlockingQueue<Integer> queue;
int threadNumber;
printerHell ph;
myRunnableHell(BlockingQueue<Integer> queue, int threadNumber,printerHell ph) {
this.queue=queue;
this.threadNumber=threadNumber;
this.ph=ph;
};
int currentNumber;
@Override
public void run() {
for(int i=0;i<queue.size();i++)
{
currentNumber=queue.remove();
if(threadNumber%3==currentNumber)
{
ph.print(currentNumber);
}
}
}
}
class printerHell {
public synchronized void print(int Number)
{
System.out.println(Number + "printed by" + Thread.currentThread().getName());
}
}
【问题讨论】：
-
请将您的标题更改为描述问题的内容。暂时没用。
-
另外，查看 Ping-Pong 多线程示例。这是同一个问题。
-
@SotiriosDelimanolis ：我更新了标题，希望现在看起来不错。我不明白如何将此号码作为共享资源打印？似乎每个线程都看到了自己的副本。你能在我做错的地方给我一些启发吗？我正在努力解决这个问题，花了大约 4-5 个小时但没有到达任何地方:(
标签： java multithreading concurrency java.util.concurrent