用两个线程连续读取一个数组 [英] Reading an array consecutively with two threads

问题描述

我有一个数组:int [] arr = {5,4,3,1,2};

I have an array : int[] arr = {5,4,3,1,2};

 I want to do like this::

 5 should be read by thread one
 4 should be read by thread two
 3 should be read by thread one
 1 should be read by thread two
 2 should be read by thread one

我已经尽力了这个简单的程序:

I have tried my best this simple program:

package com.techighost.create.deadlock;

public class ArrayReading implements Runnable {

    volatile int index = 0;

    int[] arr;

    public ArrayReading(int[] arr) {
        this.arr = arr;
    }

    @Override
    public void run() {
        synchronized (arr) {
            for (;index<=(arr.length-1);) {
                if (index % 2 == 0  && Thread.currentThread().getName().equals("Thread-One")) {
                    System.out.println(arr[index] + " " + Thread.currentThread().getName());
                    index++;
                    arr.notify();

                } else if (index % 2 != 0 && Thread.currentThread().getName().equals("Thread-Two")) {
                    System.out.println(arr[index] + " " + Thread.currentThread().getName());
                    index++;
                    arr.notify();

                }else{
                    System.out.println("In else " + Thread.currentThread().getName());
                    try {
                        arr.wait();
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
            }
        }
    }

    public static void main(String[] args) throws InterruptedException {
        int[] arr = { 5, 4, 3, 1, 2 };
        ArrayReading arrayReading = new ArrayReading(arr);
        Thread t = new Thread(arrayReading);
        t.setName("Thread-One");
        Thread t1 = new Thread(arrayReading);
        t1.setName("Thread-Two");

        t.start();
        t1.start();

        t.join();
        t1.join();
    }
}

我认为该线程名称检查不应该存在吗?任何机构都请提出可以删除该支票的建议

推荐答案

您可以使用@ zzk.Program中提到的条件 因为可以是

You can use condition as mentioned by @zzk.Program for this can be as

import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.ReentrantLock;

public class PrintSequentially {

private final int[] items;
private final ReentrantLock lock;
private final Condition notEven;
private final Condition notOdd;

private int currentCount = 0;

public PrintSequentially(int[] items) {
    this.items = items;
    this.lock = new ReentrantLock();
    this.notEven = lock.newCondition();
    this.notOdd = lock.newCondition();
}

public void printSeq() throws InterruptedException {

    try {
        lock.lockInterruptibly();
        while (currentCount < items.length) {
            if (currentCount % 2 == 0) {
                System.out.println(Thread.currentThread().getName() + ":"
                        + items[currentCount++]);
                if (currentCount < items.length)
                    notEven.await();
                notOdd.signal();
            } else {
                System.out.println(Thread.currentThread().getName() + ":"
                        + items[currentCount++]);
                notEven.signal();
                if (currentCount < items.length)
                    notOdd.await();
            }
        }

    } finally {
        lock.unlock();
    }
}

}

为此的驱动程序是

public static void main(String[] args) {
    int arr[] ={1,2,3,4,5};
    final PrintSequentially p = new PrintSequentially(arr);

    Runnable r1 = new Runnable() {
        @Override
        public void run() {
            try {
                p.printSeq();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    };

    Runnable r2 = new Runnable() {
        @Override
        public void run() {
            try {
                p.printSeq();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    };

    Thread th1 = new Thread(r1);
    th1.setName("thread 1");
    th1.start();

    Thread th2 = new Thread(r2);
    th2.setName("thread 2");
    th2.start();

}

在这里您可以添加任意多个线程.它将顺序打印.

Here you can add as many thread you want. It will print sequentially.

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