Question

I create a Preferences class and for the Getters I wan’t to use Runtime-Type Token.

So here is my getter method:

public <T> T get(String key, Class<T> clazz) {
    // do some crazy stuff (e.g. Double <-> Float)
}

Up to that, everything works fine. But I would like that the class parameter will be optional.

boolean b = preferences.get(key);

So I add an additional method:

public <T> T get(String key) {
    // return get(key, Class<T>);
}

Now the Question: Is there a way to do that? Is there a way to get an/the instance of Class<T>.

It’s possible with a small workaround:

public <T> T get(String key, T... args) {
    return get(key, (Class<T>) args.getClass().getComponentType());
}

public <T> T get(String key, Class<T> clazz) {
    System.out.println("key  : " + key);
    System.out.println("clazz: " + clazz);
}

// using
Boolean b = get("mykey");

Answer 1

It’s possible with a small workaround.

public <T> T get(String key, T... args) {
    return get(key, (Class<T>) args.getClass().getComponentType());
}

public <T> T get(String key, Class<T> clazz) {
    System.out.println("key  : " + key);
    System.out.println("clazz: " + clazz);
}

// using
Boolean b = get("mykey");

Jep I don’t like the varargs too, but it works so far.