In a relational database, locking refers to actions taken to prevent data from changing between the time it is read and the time is used.
Annotations, a form of metadata, provide data about a program that is not part of the program itself. Annotations have no direct effect on the operation of the code they annotate. Annotations have been a powerful part of Java, but most times we tend to use them rather than create them.
Mockito is a mocking framework. It is a Java-based library used to create simple and basic test APIs for performing unit testing of Java applications. It internally uses the Java Reflection API to generate mock objects for a specific interface. Mockito is in top 10 Java library across all libraries, not only the testing tools.
JUnit is a unit testing framework for the Java programming language. JUnit is used primarily to test each and every unit or component of your application, like classes and methods. It helps to write and run repeatable automated tests to ensure your code runs as intended.
All JavaBeans are POJOs but not all POJOs are JavaBeans.