In Java, we use the final keyword to prevent some classes from being extended. Simply prefix a class header with final, as in final class Password.

Ensure a variable is unchanged within a method. When Java’s static and final keywords are combined, a class-level variable can be made constant, which essentially turns it into a global variable. This ...

Java has the Boolean type, so you actually have the keywords 'true' and 'false' in your code. C, for example, doesn't so it doesn't evaluate to 0. C doesn't have the Boolean type, it's just an int.