Generic type as parameter in Java Method

Question

Do you think it is possible to create something similar to this?

private ArrayList increaseSizeArray(ArrayList array_test, GenericClass) {
    array_test.ad         


        

Answer 1

Yes, you can.

private static <T> List<T> pushBack(List<T> list, Class<T> typeKey) throws Exception {
    list.add(typeKey.getConstructor().newInstance());
    return list;
}

Usage example:

List<String> strings = new ArrayList<String>();
pushBack(strings, String.class);

Answer 2

simple solution!

private <GenericType> ArrayList increaseSizeArray(ArrayList array_test, GenericType genericObject)
{
    array_test.add(new genericObject());
    return ArrayList;
}

Answer 3

Old question but I would imagine this is the preferred way of doing it in java8+

public <T> ArrayList<T> dynamicAdd(ArrayList<T> list, Supplier<T> supplier) {
  list.add(supplier.get());
  return list;
}

and it could be used like this:

AtomicInteger counter = ...;
ArrayList<Integer> list = ...;

dynamicAdd(list, counter::incrementAndGet);

this will add a number to the list, getting the value from AtomicInteger's incrementAndGet method

Also possible to use constructors as method references like this: MyType::new