Factory. This is a design pattern. It is used to unify the creation of a diverse group of objects with a common ancestor. As with other design patterns, it helps simplify large programs.Factory
Guava. The Google Java library, called Guava, offers additional classes. For example, an ImmutableList cannot be modified. With Splitter and Joiner we handle strings.ImmutableListJoinerListMultimapSplitter
A review. Java has many classes. But using the most common ones is a good idea. Much like a musical symphony, the flow of a Java program is important.