Try to queue threads of clients but there is something wrong!

Question

Hello. I have been trying to queue threads of clients in multithreaded server but there is a problem none of the threads is alive.
here is my code.
class queueClient extends Thread{
HandleServer sa1;
LinkedList queue = new LinkedList();
queueClient(){
super();
}//end of costructor
/**method in the queueClient class to put each client in the queue*/
public void queuethem(HandleServer s){
try{
s.wait();
queue.add(s);
catch(InterruptedException sleep){
System.exit(0);
}//end of queuethem
/**method in the queueClient class to manage the clients in the queue*/
public void manageQueue(HandleServer sa){
if(!queue.isEmpty() && (queue.size())==1){
sa= (HandleServer)queue.removeFirst();
sa.notify();
sa.start();
else if (!queue.isEmpty() && (queue.size()>1)){
sa= (HandleServer)queue.removeFirst();
sa.notify();
sa.start();
try {
if(sa.currentThread().isAlive()){
sa1= (HandleServer)queue.removeFirst();
sa1.join();
else{
sa1.notify();
sa1.start();
catch (InterruptedException join) {
System.exit(0);
else{
System.out.println("Queue is empty");
}//end manageQueue
}//queueClient class end

Answer 1

ok lets say that i have 3 clients connected to my server which is responsible to pass the messages from only one client to a robot.
Ok ?
Then this server must queue the other two clients and leave only one "Alive" and the other two must wait a certain amount of time untill the current client that speaks with the server and the robot to die and then to wake up the other one client and start to talk with the server and the robot
now is it more clear?