Java @Deprecated Annotation

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In this quick article, we will discuss what is the use of @Deprecated annotation with examples.

From Oracle Java Doc: A program element annotated @Deprecated is one that programmers are discouraged from using, typically because it is dangerous, or because a better alternative exists. Compilers warn when a deprecated program element is used or overridden in non-deprecated code.

Let me put in a simple way, the @Deprecated annotation is used for informing the compiler that the particular method, class or field is deprecated and it should generate a warning when someone tries to use any of them.

The below diagram shows the internal implementation of @Deprecated annotation for your reference:

Let's demonstrates the usage @Deprecated annotation with examples.

@Deprecated annotation Example

class DeprecatedDemo { /* @deprecated This field is replaced by   * MAX_NUM field  */ @Deprecated int num = 10; final int MAX_NUM = 10; /* @deprecated As of release 1.5, replaced   * by myMsg2(String msg, String msg2)  */ @Deprecated public void myMsg() { System.out.println("This method is marked as deprecated"); } public void myMsg2(String msg, String msg2) { System.out.println(msg + msg2); } public static void main(String a[]) { DeprecatedDemo obj = new DeprecatedDemo(); obj.myMsg(); System.out.println(obj.num); } }

Output:

This method is marked as deprecated 10 

In the above example, we have a deprecated method and a deprecated field. As you can see that we have marked both of them using @Deprecated annotation and in the comment section we have used @Deprecated Javadoc tag (for documentation purpose) to inform the programmer what to use in place of it.

Reference

https://docs.oracle.com/javase/8/docs/api/java/lang/Deprecated.html