When using Java, we often write classes and algorithms that work around certain data types. Let’s look at the following class as an example:

public class StringBox {
  public String myString;
} 

In the example above we have a StringBox class which represents a real-world box of words. This class’s methods perform all of its computation with regards to the String myString field, but what if we wanted a box of ints? We could create a new class:

public class IntegerBox {
  public int myInt;    
} 

The example above meets our requirements but as the program grows and we need more types of boxes it will become unmanageable. We can solve this problem by using generics.

Generics, like the name implies, allow us to create generic classes and algorithms by specifying a type parameter. We can make StringBox and IntegerBox into a generic Box class as follows:

public class Box<T> {
  private T data;
}

In the example above, we’ve created a generic Box class with a type parameter T and all class methods performing their computation around the T type parameter. We can now specify we want a String, Integer, or any other type Box by specifying a type argument.

Over the course of this lesson, we’ll continue learning about generics in Java and their use cases.