Summarize the role and history of Java annotations.
The “@” annotation was introduced in Java 1.5,
- It was born as a comment that gives a hint to the compiler like
Benefits of using annotations.
Code correctness: annotations such as
@Overridecan add important semantic information to methods and fields and force the compiler to enforce that information. it can.
Test method: Until the advent of TestNG and annotations, JUnit used reflection to determine that a method was a test method. This determination required special naming conventions.
Adopting annotations eliminates the need to use naming conventions.
Persistence (Hibernate etc.): By adding annotations, fields and methods can be associated with the data stored in the database.
Dependency injection: Annotation can be added to the class that needs to be injected to indicate that.
Frequently used annotations
- Can be attached to fields and method parameters, and variables can have null values Please specify.
- This annotation is very useful and many tools that use the Java compiler (javac) (main IDEs are a good example) recognize the two.
- Try to use this annotation whenever possible. You should immediately notice a dramatic decrease in the number of null pointer exceptions in your codebase.
Required since Java 6.
- This annotation must be added to all methods that override the methods of the parent interface or class.
Unintentionally overriding a method with this addition
- On the contrary, it is possible to prevent a situation where you think that you have “overridden” a method that you have not overridden due to a typo.
Referenced article (Thank you always)