Example of Duck Typing in Java

Question

I have been reading examples of representations of Duck Typing in Java with reflection. I would like to know if this is correct:

public interface Quackable {
    public void quack();
}

In main...

Object[] vec = {(Here I add some instances)};

for(int i=0; i < vec.length; i++) {
    if(vec[i] instanceof Quackable)
        vec[i].quack();
}

Correct in what manner? Your code is correct but there's no duck typing here. — Maroun, Nov 26 '14 at 14:25
Why not just create the array of type Quackable[] (or a List of type Quackable). — Invisible Arrow, Nov 26 '14 at 14:25
Well, the idea is to know in execution time if an instance implements the Quackable Interface. If it does, then it can quack. Isn't that duck typing? — gibarsin, Nov 26 '14 at 14:33

Grzegorz Żur · Accepted Answer · 2014-11-26T14:37:05.967

There is no duck typing in Java as it is in Python. You can use reflection to find if the class has a method you want to call but it is really a hassle.

It looks like that

Class<?> aClass = object.getClass();
try {
    Method method = aClass.getMethod("methodName", argType1, argType2);
    method.invoke(arg1, arg2)
} catch (NoSuchMethodException | SecurityException e) {
    e.printStackTrace();
}

It is also not possible in every environment. If security manager is enabled your code should have sufficient rights to execute the code above. That also adds substantial work.

Example of Duck Typing in Java

1 Answers1