44 lines
1.1 KiB
Plaintext
44 lines
1.1 KiB
Plaintext
Utility classes, which are collections of ``++static++`` members, are not meant to be instantiated. Even abstract utility classes, which can be extended, should not have public constructors.
|
|
|
|
|
|
Java adds an implicit public constructor to every class which does not define at least one explicitly. Hence, at least one non-public constructor should be defined.
|
|
|
|
== Noncompliant Code Example
|
|
|
|
----
|
|
class StringUtils { // Noncompliant
|
|
|
|
public static String concatenate(String s1, String s2) {
|
|
return s1 + s2;
|
|
}
|
|
|
|
}
|
|
----
|
|
|
|
== Compliant Solution
|
|
|
|
----
|
|
class StringUtils { // Compliant
|
|
|
|
private StringUtils() {
|
|
throw new IllegalStateException("Utility class");
|
|
}
|
|
|
|
public static String concatenate(String s1, String s2) {
|
|
return s1 + s2;
|
|
}
|
|
|
|
}
|
|
----
|
|
|
|
== Exceptions
|
|
|
|
When class contains ``++public static void main(String[] args)++`` method it is not considered as utility class and will be ignored by this rule.
|
|
|
|
ifdef::env-github,rspecator-view[]
|
|
== Comments And Links
|
|
(visible only on this page)
|
|
|
|
include::../comments-and-links.adoc[]
|
|
endif::env-github,rspecator-view[]
|