传递SwingWorker输出并使用Future

Question

我目前有一个程序，它在后台运行多个线程。应将所有输出数据传递给单个线程，然后处理，显示并连续追加到文件。我一直在传递空值，并且无法弄明白为什么。

我试图从doInBackground（）方法传递一个字符串，我也尝试发布结果

//Code to initialize threads

    new Thread(new ProcessOutputs()).start();

    ExecutorService pool = Executors.newFixedThreadPool(3);

    Set<String> deviceSet = PingUtilityMain.devices.keySet();
    Iterator<String> it = deviceSet.iterator();

    while(it.hasNext()){
        PingShip callPing;
        try {
            callPing = new PingShip(PingUtilityMain.devices.get(it.next()));
            Future future = pool.submit(callPing);
            pingOutputs.add(future);
        } catch (Exception e) {
            System.out.println("Executor Error");
        }
    }


//
//
//
public class PingShip extends SwingWorker<String, String>{
    protected String doInBackground(){
    //task
    //publish(outputString);
    return outputString;
}

//
//
//

public class ProcessOutputs extends SingWorker<Void, Void>{
protected Void doInBackground(){
Future<String> pingOutput = PingUtility.pingOutputs.get(0);  //This is the first value  of an arraylist containing all outputs
    String output = pingOutput.get();
//Task
PingUtility.pingOutputs.remove(0);
    }
    }