如何修复Java中的“错误：找不到符号”错误？

Question

我正在用Java编写多线程代理服务器应用程序，并且不断出现此错误。我在做什么错了？

这是我ProxyApp.java文件类中的代码

/**
 * Listens to port and accepts new socket connections. 
 * Creates a new thread to handle the request and passes it the socket connection and continues listening.
 */
public void listen(){

    while(running){
        try {
            // serverSocket.accept() Blocks until a connection is made
            Socket socket = serverSocket.accept();

            // Create new Thread and pass it Runnable RequestHandler
            RequestHandler request = new RequestHandler(socket);
            Thread thread = new Thread(request);

            // Key a reference to each thread so they can be joined later if necessary
            servicingThreads.add(thread);

            thread.start(); 
        } catch (SocketException e) {
            // Socket exception is triggered by management system to shut down the proxy 
            System.out.println("Server closed");
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

所引用的RequestHandler.java文件类中的函数

/**
     * Creates a RequestHandler object capable of servicing HTTP(S) GET requests
     * @param clientSocket socket connected to the client
     */
    public RequestHandler(Socket clientSocket){
        this.clientSocket = clientSocket;
        try{
            this.clientSocket.setSoTimeout(2000);
            proxyToClientBr = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
            proxyToClientBw = new BufferedWriter(new OutputStreamWriter(clientSocket.getOutputStream()));
        } 
        catch (IOException e) {
            e.printStackTrace();
        }
    }

我在终端上遇到的错误

MacBook-Pro-de-Marcos:mwmv marcosvicente$ javac RequestHandler.java
MacBook-Pro-de-Marcos:mwmv marcosvicente$ javac proxyApp.java
proxyApp.java:10: error: cannot find symbol
import ru.novsu.povt.mwmv.RequestHandler;
                         ^
  symbol:   class RequestHandler
  location: package ru.novsu.povt.mwmv
proxyApp.java:122: error: cannot find symbol
                RequestHandler request = new RequestHandler(socket);
                ^
  symbol:   class RequestHandler
  location: class proxyApp
proxyApp.java:122: error: cannot find symbol
                RequestHandler request = new RequestHandler(socket);
                                             ^
  symbol:   class RequestHandler
  location: class proxyApp
3 errors