16f6c0aecf
Inline adoc files when they are included exactly once. Also fix language tags because this inlining gives us better information on what language the code is written in.
61 lines
1.3 KiB
Plaintext
61 lines
1.3 KiB
Plaintext
== Why is this an issue?
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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.
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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.
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=== Noncompliant code example
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[source,java]
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----
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class StringUtils { // Noncompliant
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public static String concatenate(String s1, String s2) {
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return s1 + s2;
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}
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}
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----
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=== Compliant solution
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[source,java]
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----
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class StringUtils { // Compliant
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private StringUtils() {
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throw new IllegalStateException("Utility class");
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}
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public static String concatenate(String s1, String s2) {
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return s1 + s2;
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}
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}
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----
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=== Exceptions
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When class contains ``++public static void main(String[] args)++`` method it is not considered as utility class and will be ignored by this rule.
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ifdef::env-github,rspecator-view[]
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'''
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== Implementation Specification
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(visible only on this page)
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=== Message
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Hide this public constructor.
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Add a private constructor to hide the implicit public one.
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'''
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== Comments And Links
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(visible only on this page)
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include::../comments-and-links.adoc[]
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endif::env-github,rspecator-view[]
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