Generics are a way of writing generic, reusable code without specifying a type. You can write a generic function that may not be limited to one type. It's possible to create generic functions as well as generic types that add type restrictions. You have used generic types in this book even without noticing it.
The main idea behind generics is that instead of specifying a type, you use a generic type placeholder. Generics are a great tool for removing code duplication and making code reusable.
The first step is to identify the code that can be generic. The best way to do this is by asking, "Is this functionality limited only to this type or not?" If you realize that it is not, you should consider making it generic.
Tip
Make functions generic only if you need to do so and if you are going to use them with different types. Making them generic could have a slightly negative impact on performance.
Let's create our first simple generic function. Our printMe function can work only with integers...