Deep Copy of a Generic Type in Java

问题:

How does deep copies (clones) of generic types T, E work in Java? Is it possible?

E oldItem;
E newItem = olditem.clone(); // does not work

回答1:

The answer is no. Cause there is no way to find out which class will replace your generic type E during compile time, unless you Bind it to a type.

Java way of cloning is shallow, for deep cloning, we need to provide our own implementation

The work-around for it, is to create a contract like this

public interface DeepCloneable {
    Object deepClone();
}

and an implementor should be having its own deep-clone logic

class YourDeepCloneClass implements DeepCloneable {

    @Override
    public Object deepClone() {
        // logic to do deep-clone
        return new YourDeepCloneClass();
    }

}

and it can be called like below, where the generic type E is a bounded type

class Test<E extends DeepCloneable> {

    public void testDeepClone(E arg) {
        E e = (E) arg.deepClone();
    }
}