創建一個數組blockingqueue

Question

我正在實現多線程，並希望能夠發送/接收消息從/從每個線程從主。所以，我想建立一個阻塞隊列與下面的代碼的每個線程：

public static void main(String args[]) throws Exception { 
    int deviceCount = 5; 
    devices = new DeviceThread[deviceCount]; 
    BlockingQueue<String>[] queue = new LinkedBlockingQueue[5]; 

    for (int j = 0; j<deviceCount; j++){ 
     device = dlist.getDevice(); //get device from a device list 
     devices[j] = new DeviceThread(queue[j], device.deviceIP, port, device.deviceID, device.password); 
     queue[j].put("quit"); 
    } 
} 


public class DeviceThread implements Runnable { 
    Thread t; 
    String ipAddr; 
    int port; 
    int deviceID; 
    String device; 
    String password; 
    BlockingQueue<String> queue; 


    DeviceThread(BlockingQueue<String> q, String ipAddr, int port, int deviceID, String password) { 

     this.queue=q; 
     this.ipAddr = ipAddr; 
     this.port = port; 
     this.deviceID = deviceID; 
     this.password = password; 
     device = "device"+this.deviceID; 
     t = new Thread(this, device); 
     System.out.println("device created: "+ t); 
     t.start(); // Start the thread 
    } 

    public void run() { 
     while(true){ 
      System.out.println(device + " outputs: "); 
      try{ 
       Thread.sleep(50); 
       String input =null; 
       input = queue.take(); 
       System.out.println(device +"queue : "+ input); 
      }catch (InterruptedException a) { 

      } 

     } 

    } 
} 

代碼編譯，但在運行時，它給我一個NullPointerException上線queue[j].put("quit");

它只有1隊列工作BlockingQueue queue = new LinkedBlockingQueue(5);

我相信它，因爲數組心不是正確的初始化，我想聲明爲BlockingQueue[] queue = new LinkedBlockingQueue10;，但它給了我「;預計」

人知道如何解決這一問題？我正在使用netbeans IDE 7.3.1。

謝謝。

Answer 1

BlockingQueue<String>[] queue = new LinkedBlockingQueue[5]; 

創建一個空引用數組。你需要實際初始化每一個：

for(int i=0; i<queue.length; i++){ 
    queue[i]=new LinkedBlockingQueue(); //change constructor as needed 
}