36 lines
922 B
Plaintext
36 lines
922 B
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.
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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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----
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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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----
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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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