Create instance of generic type in Java?

Question

Is it possible to create an instance of a generic type in Java? I\'m thinking based on what I\'ve seen that the answer is no (due to type erasure), but

Answer 1

In Java 8 you can use the Supplier functional interface to achieve this pretty easily:

class SomeContainer {
  private Supplier supplier;

  SomeContainer(Supplier supplier) {
    this.supplier = supplier;
  }

  E createContents() {
    return supplier.get();
  }
}

You would construct this class like this:

SomeContainer stringContainer = new SomeContainer<>(String::new);

The syntax String::new on that line is a constructor reference.

If your constructor takes arguments you can use a lambda expression instead:

SomeContainer bigIntegerContainer
    = new SomeContainer<>(() -> new BigInteger(1));