業(yè)務(wù)邏輯是相同的：

給定一個(gè)由訪問次數(shù)/時(shí)間組成的String表達(dá)式，例如：“ 1 / 24h，1..3 / 3h，5 / *”

然后，結(jié)果應(yīng)為以下字符串列表：

“ 1 / 24h”，
“ 1 / 3h”，“ 2 / 3h”，“ 3 / 3h”，
“ 5 / 1h”，“ 5 / 2h”，“ 5 / 3h”，“ 5 / 4h”，“ 5 / 5h”，直到“ 24 / 1h”

因此，需要解決2件事，即訪問點(diǎn)和時(shí)間點(diǎn)和星星。

我將使用Java 8，但我將向您展示使用Functional實(shí)現(xiàn)此邏輯與使用循環(huán)和ifs以傳統(tǒng)方式實(shí)現(xiàn)此邏輯之間的區(qū)別。

package com.marco; import java.util.ArrayList; import java.util.List; import java.util.function.Function; import java.util.stream.Collectors; import com.google.common.collect.ImmutableList; import com.google.common.collect.Lists; public class ExpressionConverter {private static final String COMMA = ",";private static final String SEPARATOR = "/";private final ImmutableList<Function<String, List<String>>> visitFunctions;private final ImmutableList<Function<String, List<String>>> timeFunctions;public ExpressionConverter(DotsVisitFunction dotsVisitFunction, StarVisitFunction starVisitFunction, StandardFunction standardFunction,StarTimeFunction starTimeFunction) {this.visitFunctions = ImmutableList.of(dotsVisitFunction, starVisitFunction, standardFunction);this.timeFunctions = ImmutableList.of(starTimeFunction, standardFunction);}public List<String> convertVisitTimeExpressionFunctional(String visitTimeExpression) {return Lists.newArrayList(visitTimeExpression.split(COMMA)).parallelStream().filter(it -> !it.isEmpty()).map(it -> interpretSingleExpressionFunctional(it)).flatMap(it -> it.parallelStream()).collect(Collectors.toList());}public List<String> convertVisitTimeExpressionTraditional(String visitTimeExpression) {List<String> result = new ArrayList<String>();for (String singleVisitTime : visitTimeExpression.split(COMMA)) {if (!singleVisitTime.isEmpty()) {result.addAll(interpretSingleVisitTimeExpressionTraditional(singleVisitTime));}}return result;}private List<String> interpretSingleExpressionFunctional(String singleExpression) {String visit = singleExpression.split(SEPARATOR)[0];String time = singleExpression.split(SEPARATOR)[1];List<String> result = Lists.newArrayList();visitFunctions.stream().map(it -> it.apply(visit)).flatMap(it -> it.stream()).forEach(visitIt -> {timeFunctions.stream().map(it -> it.apply(time)).flatMap(it -> it.stream()).forEach(timeIt -> {result.add(visitIt + SEPARATOR + timeIt);});});return result;}private List<String> interpretSingleVisitTimeExpressionTraditional(String singleExpression) {String visit = singleExpression.split(SEPARATOR)[0];String time = singleExpression.split(SEPARATOR)[1];List<String> result = Lists.newArrayList();List<String> visists = Lists.newArrayList();List<String> times = Lists.newArrayList();for (Function<String, List<String>> visitFunction : visitFunctions) {visists.addAll(visitFunction.apply(visit));}for (Function<String, List<String>> timeFunction : timeFunctions) {times.addAll(timeFunction.apply(time));}for (String visitIt : visists) {for (String timeIt : times) {result.add(visitIt + SEPARATOR + timeIt);}}return result;} }

如您所見，我們有2種公共方法和2種私有方法（功能方法和傳統(tǒng)方法）。

這是一個(gè)針對這兩種樣式的性能的簡單測試：

package com.marco; import static org.mockito.Matchers.any; import static org.mockito.Matchers.anyInt; import static org.mockito.Matchers.anyLong; import static org.mockito.Mockito.mock; import static org.mockito.Mockito.when; import java.math.BigDecimal; import java.util.Set; import org.junit.Before; import org.junit.Test; import com.google.common.collect.ImmutableSet; import com.google.common.collect.Sets; public class ExpressionConverterTest {private static final String EXPRESSIONS = "6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,6/7400,9/65h,55..57/14400";private Cache cache;private ExpressionConverter expressionConverter;@Beforepublic void init() {cache = mock(Cache.class);expressionConverter = new ExpressionConverter(new DotsVisitFunction(cache), new StarVisitFunction(cache), new StandardFunction(),new StarTimeFunction(cache));Set<Integer> totVisists = Sets.newHashSet();for (int i = 1; i <= 100; i++) {totVisists.add(i);}when(cache.getVisits(anyLong(), (BigDecimal) any(), anyInt())).thenReturn(ImmutableSet.copyOf(totVisists));}@Testpublic void testPerf() {long averageTraditional = 0l;long averageFuntional = 0l;for (int a = 0; a < 10; a++) {long start = System.currentTimeMillis();for (int i = 0; i < 1000; i++) {expressionConverter.convertVisitTimeExpressionTraditional(EXPRESSIONS);}System.out.println("Traditional java " + (System.currentTimeMillis() - start) + " ms");averageTraditional += (System.currentTimeMillis() - start);long start2 = System.currentTimeMillis();for (int i = 0; i < 1000; i++) {expressionConverter.convertVisitTimeExpressionFunctional(EXPRESSIONS);}System.out.println("Functional java " + (System.currentTimeMillis() - start2) + " ms");averageFuntional += (System.currentTimeMillis() - start2);}System.out.println("Average Traditional java : " + (averageTraditional / 10) + " ms");System.out.println("Average Functional java : " + (averageFuntional / 10) + " ms");} }

這是輸出：

Traditional java 1274 msFunctional java 773 msTraditional java 1054 msFunctional java 531 msTraditional java 961 msFunctional java 493 msTraditional java 948 msFunctional java 492 msTraditional java 949 msFunctional java 491 msTraditional java 958 msFunctional java 481 msTraditional java 1004 msFunctional java 474 msTraditional java 949 msFunctional java 471 msTraditional java 947 msFunctional java 475 msTraditional java 942 msFunctional java 472 msAverage Traditional java : 998 msAverage Functional java : 515 ms

功能是傳統(tǒng)的2倍。 為什么？

因此：parallelStream（）

Parallel Stream將利用您的多核系統(tǒng)將工作分解為多個(gè)任務(wù)。

因此，您可以將parallelStream（）放在任何地方，并用parallelStream（）替換所有stream（）方法嗎？

沒有！

如果在錯(cuò)誤的地方使用parallelStream（）實(shí)際上會導(dǎo)致性能大大降低。

在使用此功能之前，應(yīng)閱讀有關(guān)此參數(shù)的大量文章，但請記住，如果要使用parallelStream（），請確保在測量前后的性能！！！！

翻譯自: https://www.javacodegeeks.com/2014/08/java-8-functional-vs-traditional.html

總結(jié)

以上是生活随笔為你收集整理的Java 8：功能性VS传统的全部內(nèi)容，希望文章能夠幫你解決所遇到的問題。

如果覺得生活随笔網(wǎng)站內(nèi)容還不錯(cuò)，歡迎將生活随笔推薦給好友。