Convert one object to another using generics

Question

I have two classes Foo1 and Foo2 very similar fields. And I have a convert method that accepts Foo1 class as shown below

public static <T> T convert(IFoo1 foo1, Class<T extends IFoo2> clz) {
    T foo2 = clz.newInstance();
    // Setter methods
    return foo2; 
}

But I'm getting error : Syntax error on token "extends", , expected

Both the classes Foo1 and Foo2 implements interface IFoo1 and IFoo2.

Also, this seems like a poor use of generics. – KG6ZVP Sep 27 '18 at 22:02 — KG6ZVP, Sep 27 '18 at 22:02

score 3 · Accepted Answer · answered Sep 27 '18 at 22:09

The error you are getting is because your generic is using improper bounding.

Change your method declaration to:

public static <T extends IFoo2> T convert(IFoo1 foo1, Class<T> clz) {
    T foo2 = clz.newInstance();
    ....
    return foo2; 
}

There is another type of bounding you may have been thinking of. I recommend reading this SO question: Understanding upper and lower bounds on ? in Java Generics

1 Answers1