Hashtables: What on earth is wrong with the following code!?

Question

I'm loosing my mind here:
[jdk1.4.2]
//random code...
        Hashtable threads = new Hashtable(20);
        threads.put(portNum, ipThread); //portNum is of type int
                                        //ipThread is of type ThreadX, ThreadX extends Thread
//other code...
        ThreadX t;
        t = (ThreadX)threads.get(packet.getPort());  //packet.getPort() returns an INTAnd the compiler returns this:
path>javac *.java
IPServer.java:58: cannot resolve symbol
symbol : method put (int,ThreadX)
location: class java.util.Hashtable
threads.put(destinationPort, ipThread);
^
IPServer.java:67: cannot resolve symbol
symbol : method get (int)
location: class java.util.Hashtable
t = (ThreadX)threads.get(packet.getPort());
^
2 errors
Thanks ahead of time.

Answer 1

From the JDK 1.4.2 documentation
"This class implements a hashtable, which maps keys to values. Any non-null object can be used as a key or as a value.
To successfully store and retrieve objects from a hashtable, the objects used as keys must implement the hashCode method and the equals method. "
I assumed from that an int or double or any other primitive, which implements both the hashCode and equals method, would work.