Java 8 introduces few general purpose functional interfaces based on the input and output to the single abstract method.

Most common ones are:

1. Predicate<T> whose method

   1. takes in an argument of type T and

   2. rerturn a boolean.

2. Consumer<T> whose method

   1. takes in an argument of type T and

   2. rerturn nothing (void).

3. Function<T,R> whose method

In functional programming, we think in terms of functions. While Object Oriented programming abstract over data, functional programming abstract over behavior. Instead of data, stateless functions are be passed across the code. 

Lambda expressions are Java's way of doing functional programming. Lambda expressions in computer science are anonymous functions: a function (or a subroutine) defined, and possibly called, without being bound to an identifier.

​

Git is a Distributes Version Control System for tracking changes in computer files and coordinating work on those files among multiple people.

It is primarily used for source code management in software development,[8] but it can be used to keep track of changes in any set of files. 

This is a quick summary of important annotations in Spring for doing core tasks in Spring. Some of them might have already been covered in examples. Some of them might be covered later. Some of them might be a variation of the already covered ones, so please feel free to try them out and let us know if you face any issues.

@Configuration, @Bean

You can use @Configuration to specify a Java configuration file. 

@Profile annotation allow you to register components that will be selected only if its associated profile is active. You can selectively activate a set of beans in a class or all beans .