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.
80 lines
2.0 KiB
Plaintext
80 lines
2.0 KiB
Plaintext
== Why is this an issue?
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Just as there is little justification for writing your own String class, there is no good reason to re-define one of the existing, standard functional interfaces.
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Doing so may seem tempting, since it would allow you to specify a little extra context with the name. But in the long run, it will be a source of confusion, because maintenance programmers will wonder what is different between the custom functional interface and the standard one.
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=== Noncompliant code example
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[source,java]
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----
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@FunctionalInterface
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public interface MyInterface { // Noncompliant
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double toDouble(int a);
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}
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@FunctionalInterface
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public interface ExtendedBooleanSupplier { // Noncompliant
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boolean get();
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default boolean isFalse() {
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return !get();
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}
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}
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public class MyClass {
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private int a;
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public double myMethod(MyInterface instance){
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return instance.toDouble(a);
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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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@FunctionalInterface
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public interface ExtendedBooleanSupplier extends BooleanSupplier { // Compliant, extends java.util.function.BooleanSupplier
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default boolean isFalse() {
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return !getAsBoolean();
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}
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}
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public class MyClass {
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private int a;
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public double myMethod(IntToDoubleFunction instance){
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return instance.applyAsDouble(a);
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}
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}
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----
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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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* Drop this interface in favor of "XXX".
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* Make this interface extend "XXX" and remove the functional method declaration.
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'''
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== Comments And Links
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(visible only on this page)
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=== on 14 Sep 2018, 07:02:32 Michal Domagala wrote:
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Current implementation: 5.7.0.15470 sonar-java/java-checks/src/main/java/org/sonar/java/checks/StandardFunctionalInterfaceCheck.java
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does not recognize two well known functional interfaces, Runnable and Callable
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Link to master \https://github.com/SonarSource/sonar-java/blob/master/java-checks/src/main/java/org/sonar/java/checks/StandardFunctionalInterfaceCheck.java
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endif::env-github,rspecator-view[]
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