How to lock a function while it is in processing?

Question

i am using threads to write my game server side. anyone have any idea on how to lock a function while it is in process? then it wl continue after a process. appreciate very much

Answer 1

   public void run() {
        try {
            char charBuffer[] = new char[1];
            // --- while we have an incoming stream
            while(in.read(charBuffer,0,1) != -1) {
                // --- create a string buffer to hold the incoming stream
                StringBuffer stringBuffer = new StringBuffer(8192);
                // --- while the stream hasn't ended
                while(charBuffer[0] != '\0') {
                    // --- add the character to our buffer
                    stringBuffer.append(charBuffer[0]);
                    in.read(charBuffer, 0 ,1);
                if(stringBuffer.toString().equals("IP")){
                    getMachineId(this.getIP());
                   } else{
                    // --- analysis the XML
                    parseReceivedXML(stringBuffer.toString());
        } catch(IOException ioe) {
            server.writeActivity("Client IP: " + ip + " caused a read error "
                    + ioe + " : " + ioe.getMessage() + "and has been disconnected.");
        } finally {
            killClient();
    }above is my run() code. i want to lock the function parseReceivedXML() and release it to the waiting thread after a thread finish process. i want the threads queue up to run in this function. please help