Through Java's evolution keywords have been added. While code that uses those words as identifiers may be compilable under older versions of Java, it will not be under modern versions. 

Following keywords are marked as invalid identifiers 

[frame=all]
[cols="^1,^1"]
|===
|Keyword|Added

|``++_++``|9
|``++enum++``|5.0
|===


``++assert++`` and ``++strictfp++`` are another example of valid identifiers which became keywords in later versions, but are not supported by this rule.


== Noncompliant Code Example

[source,java]
----
public void doSomething() {
  int enum = 42;            // Noncompliant
  String _ = "";   // Noncompliant
}
----


== Compliant Solution

[source,java]
----
public void doSomething() {
  int magic = 42;  
}
----


ifdef::env-github,rspecator-view[]

'''
== Implementation Specification
(visible only on this page)

include::message.adoc[]

'''
== Comments And Links
(visible only on this page)

include::comments-and-links.adoc[]
endif::env-github,rspecator-view[]
