A method (or constructor) can be marked as deprecated using either the @Deprecated annotation or the @deprecated Javadoc tag. Using a method that has been marked as deprecated is bad practice, typically for one or more of the following reasons:

The method is dangerous.
There is a better alternative method.
Methods that are marked as deprecated are often removed from future versions of an API. So using a deprecated method may cause extra maintenance effort when the API is upgraded.

Avoid using a method that has been marked as deprecated. Follow any guidance that is provided with the @deprecated Javadoc tag, which should explain how to replace the call to the deprecated method.

Help - Eclipse Platform: Java Compiler Errors/Warnings Preferences.

Java API Specification: Annotation Type Deprecated.

Java SE Documentation: How and When To Deprecate APIs.