47 lines
1.2 KiB
Plaintext
47 lines
1.2 KiB
Plaintext
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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----
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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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----
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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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