Java-Vector类中的remove方法始终返回True

Question

Here i have my method

System.out.println("removeConnectedUser called. size connectedUsers="+connectedUsers.size());
if(connectedUsers.remove(conUser));
{
  System.out.println("Removing user "+conUser.conn.getRemoteSocketAddress().toString()+"..."+connectedUsers.size());
  writeUserAction(conUser.conn.getRemoteSocketAddress().toString(),"999");
  try
  {
    conUser.conn.close();
  }catch(IOException e){
      System.out.println("Exception in removeConnectedUser");
  }
  ServerMainPanel.updateConnectedUsers(connectedUsers.size());
}

The problem is that this method may be called more than one time, so it's executed more than necessary. To filter bad calls, i've added if(connectedUsers.remove(conUser)); but this always return true! It is the console output

Error in liveUpdate:java.net.SocketException: Connection reset by peer: socket write error
removeConnectedUser called. size connectedUsers=1
Removing user /10.175.33.179:4085 ...0
Error liveSecUpdate:java.net.SocketException: Socket closed
removeConnectedUser called. size connectedUsers=0
Removing user /10.175.33.179:4085 ...0

So, vector.remove always returns True, even if vector's size is Zero. 1- it's impossible element is removed if size()=0, 2- impossible i'm having two instances of the same object in this vector, because i have connected just one client

Answer 1

You have a spurious semicolon at the end of the if :

if(connectedUsers.remove(conUser));
                                  ^ REMOVE THIS

This makes the code block that follows execute irrespective of the if condition.