So I'm working in Java and I want to declare a generic List.
So what I'm doing so far is List<T> list = new ArrayList<T>();
But now I want to add in an element. How do I do that? What does a generic element look like?
I've tried doing something like List.add("x") to see if I can add a string but that doesn't work.
(The reason I'm not declaring a List<String> is because I have to pass this List into another function that only takes List<T> as an argument.
You should either have a generic class or a generic method like below:
public class Test<T> {
List<T> list = new ArrayList<T>();
public Test(){
}
public void populate(T t){
list.add(t);
}
public static void main(String[] args) {
new Test<String>().populate("abc");
}
}
public <T extends SomeThing> T method(T arg) (though that might be a more complicated case then OP currently has).
or generic method in my answer :)The T is the type of the objects that your list will contain.
You can write List<String> and use it in a function which needs List<T>, it shouldn't be a problem since the T is used to say that it can be anything.
You cannot add the "X"(String) into the list having type of directly so that you need to write a function which accept T as a parameter and add into the List, like
List<T> myList = new ArrayList<T>(0);
public void addValue(T t){
myList.add(t);
}
and while calling this function you can pass string.
object.addValue("X");
List<T>, which will likely be a generic argument to the class it belongs to. You're likely the one defining what thisTis somewhere in your own code.List<Object> list = new ArrayList<Object>(), and after you get an element byget(int index)downcast it to the desire class which compatible to another function.