Copying an unknown Object

Question

I have an Object that I pull from a Hashtable. I don't know what type of Object it is, nor do I care. But I need to make a copy of it and .clone() is protected on Object.
eg.
Object obj1 = hashtable.get(key);
Object obj2 = obj1.clone(); // WILL NOT COMPILE (even in a try block)
Any ideas?

Answer 1

If these objects were created by your code, then they each need to implement Cloneable and also implement a public clone() method. If you call the clone() method of Object via super.clone(), then it is a shallow copy and you'll need to copy any embedded objects yourself.
Assuming that all the classes in your Hashtable implement a public clone() method, then you'll need to either cast the reference to the appropriate class , or else use reflection to invoke the clone method.
e.gimport java.lang.reflect.*;
Object obj = yourHashtable.get("key");
try {
    Method meth = obj.getClass().getMethod("clone", null);
    try {
        Object x = meth.invoke(obj, null);
        ...do something with cloned object x...
    } catch (Exception ex) {
        System.out.println("cannot call clone method: " + ex);
} catch (NoSuchMethodException nsmex) {
    System.out.println("No public clone method exists: " + nsmex);
}