03_type-inference.md

Type Inference

A Java Compiler's ability to simplify Generics usage.

public class Box<T> {
    private T type;

    public void set(T type) {
        this.type = type;
    }

    public T get() {
        return type;
    }

    // T is a type parameter
}

public class Util {

    public static <T> void displayToString(T type) {
        System.out.println(type.toString());
    }

}

• Type Inference - Methods

  Util.<Animal>displayToString(favoriteAnimal);

  Instead of adding the <> we can do the following:

  Util.displayToString(favoriteAnimal);

  They are both correct but the second one is easier to use.

• Type Inference - Instantiation of Generic Classes

  Box<Integer> favoriteNumber = new Box<Integer>();

  Instead of having the <> on the right side can do the following:

  Box<Integer> favoriteNumber = new Box<>();

• Type Inference - Target Types

  ArrayList<String> todoList = Collections.<String>emptyList();

  Instead of having the <> on the right side can do the following:

  ArrayList<String> todoList = Collections.emptyList();