Java8 new feature--LAMBDA expression. (Case: Complete number classification)

Requirement: Enter a number to determine its type (total number, excess number, insufficient number)

Full number: All factors outside of itself and = = itself

Excess: all factors outside of itself and > itself

Insufficiency: All factors outside of itself and < itself

1 Package Cn._3.numberclassifier;2 3 //BEGIN number_classifier_java84 import java.util.List;5 import Java.util.stream.IntStream;6 7ImportStaticjava.lang.Math.sqrt;8ImportStaticjava.util.stream.Collectors.toList;9ImportStaticJava.util.stream.IntStream.range;Ten  One  Public classNumberclassifier { A  -     //BEGIN Java8_filter -      Public StaticIntstream Factorsof (intNumber ) { the         returnRange1, number +1). Filter (potential, number% potential = =0); -     } -     //END Java8_filter -      Public Static intAliquotsum (intNumber ) { +         returnFactorsof (number). SUM ()-Number ; -     } +      Public StaticBoolean Isperfect (intNumber ) { A         returnAliquotsum (number) = =Number ; at     } -      Public StaticBoolean isabundant (intNumber ) { -         returnAliquotsum (number) >Number ; -     } -      Public StaticBoolean isdeficient (intNumber ) { -         returnAliquotsum (number) <Number ; in     } -     //END number_classifier_java8 to  +     //BEGIN Java8_filter_fast -      Public StaticList<integer> Fastfactorsof (intNumber ) { thelist<integer> factors = range (1, (int) (sqrt (number) +1)) *. filter (potential, number% potential = =0). Boxed ()//back to Stream<integer> $. Collect (ToList ());//folding/approx., reducePanax Notoginsenglist<integer> factorsabovesqrt = Factors.stream (). Map (E-and number/e). Collect (ToList ()); - Factors.addall (factorsabovesqrt); the         //Change stream to ArrayList +         returnFactors.stream (). Distinct (). Collect (ToList ()); A     } the     //END Java8_filter_fast +}

Test class:

1 Package Cn._3.numberclassifier;2 3  Public classMmain {4 5      Public Static voidMain (string[] args) {6Integer number =666;7System. out. println (Numberclassifier.isperfect (number) +","+numberclassifier.isabundant (number) +","+numberclassifier.isdeficient (number));8     }9}

Java8 new feature--LAMBDA expression. (Case: Complete number classification)