用循环遍历一个线程并处理多个结果

Question

我正在尝试使用线程使我的程序运行并行运行，但我很挣扎。

目标是处理链接列表，urlList 通过 ImageProcessor().processLink 函数。我有两个问题要解决：

我如何循环它以便它在池中使用 N 个线程，在本例中为 10 个？也就是我想一次处理10个链接。
上面的处理函数returns一个File，我需要添加到一个数组，fileList。说到多线程，我将如何处理？

这是我目前得到的：

    ArrayList<String> urlList = new ArrayList<>(Arrays.asList(arr.split("\r?\n"))) ;
    ArrayList<File> fileList = new ArrayList<>();
    ExecutorService executor = Executors.newFixedThreadPool(10);

    //process the requested files
    for (int i = 0; i < urlList.size(); i++){
        Future<File> value = executor.submit(new Callable<File>() {
            @Override
            public File call(int i) throws IOException {
                return new ImageProcessor().processLink(urlList.get(i));
            }
        });

        try {
            fileList.add(value.get());
        } catch (InterruptedException e) {
            e.printStackTrace();
        } catch (ExecutionException e) {
            e.printStackTrace();
        }

    }

Answer 1

得到它与以下工作：

    ArrayList<String> urlList = new ArrayList<>(Arrays.asList(arr.split("\r?\n"))) ;
    ArrayList<File> fileList = new ArrayList<>();

    ExecutorService executor = Executors.newFixedThreadPool(THREAD_SIZE);
    List<Future<File>> futures = new ArrayList<>();

    for (int i = 0; i < urlList.size(); i++) {
        ImageProcessor proc = new ImageProcessor(urlList.get(i));
        final Future<File> future = executor.submit(proc);
        futures.add(future);
    }

    try {
        executor.awaitTermination(5, TimeUnit.SECONDS);
    } catch (InterruptedException e) {
        e.printStackTrace();
    }

    for (int i = 0; i < futures.size(); i++)
    {
        Future<File> result = futures.get(i);
        try {
            fileList.add(result.get());
        } catch (InterruptedException e) {
            e.printStackTrace();
        } catch (ExecutionException e) {
            e.printStackTrace();
        }
    }
    executor.shutdown();
    while (!executor.isTerminated()) { }
    System.out.println("Finished all threads");

用循环遍历一个线程并处理多个结果

Iterate through a thread with loop and process multiple results

java

multithreading

java-8

scheduledexecutorservice