Here's a topic I don't understand. What's the benefit of making a private constructor and a public getInstance method? I understand why you would make the constructor private: to keep someone from ...

The code we moved into the private method will only be available to that class. If you want to share it with other classes, you will no longer have this access. You could potentially create an ...

See the Java 101 Java interfaces tutorial for a more in-depth introduction to using interfaces in your Java programs, including where and where not to use default, static, and private methods.