72 lines
2.5 KiB
Java
72 lines
2.5 KiB
Java
package cn.iocoder.dashboard.util.collection;
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import cn.hutool.core.collection.CollectionUtil;
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import java.util.*;
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import java.util.function.Function;
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import java.util.function.Predicate;
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import java.util.stream.Collectors;
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/**
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* Collection 工具类
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*
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* @author 芋道源码
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*/
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public class CollectionUtils {
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public static <T> Set<T> asSet(T... objs) {
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return new HashSet<>(Arrays.asList(objs));
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}
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public static <T> List<T> filterList(Collection<T> from, Predicate<T> predicate) {
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return from.stream().filter(predicate).collect(Collectors.toList());
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}
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public static <T, U> List<U> convertList(List<T> from, Function<T, U> func) {
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return from.stream().map(func).collect(Collectors.toList());
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}
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public static <T, U> Set<U> convertSet(List<T> from, Function<T, U> func) {
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return from.stream().map(func).collect(Collectors.toSet());
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}
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public static <T, K> Map<K, T> convertMap(List<T> from, Function<T, K> keyFunc) {
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return from.stream().collect(Collectors.toMap(keyFunc, item -> item));
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}
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public static <T, K, V> Map<K, V> convertMap(List<T> from, Function<T, K> keyFunc, Function<T, V> valueFunc) {
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return from.stream().collect(Collectors.toMap(keyFunc, valueFunc));
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}
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public static <T, K> Map<K, List<T>> convertMultiMap(List<T> from, Function<T, K> keyFunc) {
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return from.stream().collect(Collectors.groupingBy(keyFunc,
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Collectors.mapping(t -> t, Collectors.toList())));
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}
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public static <T, K, V> Map<K, List<V>> convertMultiMap(List<T> from, Function<T, K> keyFunc, Function<T, V> valueFunc) {
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return from.stream().collect(Collectors.groupingBy(keyFunc,
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Collectors.mapping(valueFunc, Collectors.toList())));
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}
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// 暂时没想好名字，先以 2 结尾噶
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public static <T, K, V> Map<K, Set<V>> convertMultiMap2(List<T> from, Function<T, K> keyFunc, Function<T, V> valueFunc) {
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return from.stream().collect(Collectors.groupingBy(keyFunc, Collectors.mapping(valueFunc, Collectors.toSet())));
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}
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public static boolean containsAny(Collection<?> source, Collection<?> candidates) {
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return org.springframework.util.CollectionUtils.containsAny(source, candidates);
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}
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public static <T> T getFirst(List<T> from) {
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return !CollectionUtil.isEmpty(from) ? from.get(0) : null;
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}
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public static <T> void addIfNotNull(Collection<T> coll, T item) {
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if (item == null) {
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return;
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}
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coll.add(item);
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}
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}
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