Question

I want to wait() the put() method called from the second thread which has been connected to the Server (Monitor). But when i do this, the whole GUI frames (Swing) including their elements get frozen aftr the second put() call. How to fix this? I want the second thread keep waiting till the first thread performs a get() which frees a slot. Thanks in advance. Here’s my skeleton code:

Server:

Buffer<String> buf = new Buffer<String>(1);
while(true){
   //for each socket connected           
   new ServerHandler(..., buf).start();

}

ServerHandler:

public class ServerHandler extends Thread {

  Buffer<Messenger> buf;

  public void run(){
      buf.put("Test");
  }
}

Buffer:

public class BufferImp<String>
    private String[] requests;
    private int cur_req_in; // current Request in the queue
    private int req_size;
    private int req_count;

 public BufferImp(int size) {
        this.req_size = size;
        requests = new String[size];
        this.cur_req_in = 0;
        this.req_count = 0;
    }

 public synchronized void put(E o) throws InterruptedException {

        while(req_size == req_count) this.wait();

        requests[cur_req_in] = o;
        cur_req_in = (cur_req_in + 1) % req_size;
        req_count++;
        notifyAll();


    }
}

Answer 1

Don’t call wait when code is executing on the Event Dispatch Thread.

Instead you need to create a separate Thread for your long running task,

Read the section from the Swing tutorial on Concurrency for more information.