$.Collections3.java Source code

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Here is the source code for $.Collections3.java

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    #set($symbol_pound='#')#set($symbol_dollar='$')#set($symbol_escape='\')
/*******************************************************************************
 * Copyright (c) 2005, 2014 springside.github.io
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 *******************************************************************************/
package ${package}.biz.util;

    import org.apache.commons.beanutils.PropertyUtils;
    import org.apache.commons.lang3.StringUtils;

    import java.util.*;

    /**
     * Collections.
     * 
     * JDKCollectionsGuavaCollections2?, ??Collections3.
     * 
     * ????????Apache Commons Collection, ??
     * 
     * @author calvin
     */
    public class Collections3 {

        /**
         * ????(Getter), ??Map.
         * 
         * @param collection ???.
         * @param keyPropertyName ????MapKey??.
         * @param valuePropertyName ????MapValue??.
         */
        public static Map extractToMap(final Collection collection, final String keyPropertyName,
                final String valuePropertyName) {
            Map map = new HashMap(collection.size());

            try {
                for (Object obj : collection) {
                    map.put(PropertyUtils.getProperty(obj, keyPropertyName),
                            PropertyUtils.getProperty(obj, valuePropertyName));
                }
            } catch (Exception e) {
                throw Reflections.convertReflectionExceptionToUnchecked(e);
            }

            return map;
        }

        /**
         * ????(Getter), ??List.
         * 
         * @param collection ???.
         * @param propertyName ??????.
         */
        public static List extractToList(final Collection collection, final String propertyName) {
            List list = new ArrayList(collection.size());

            try {
                for (Object obj : collection) {
                    list.add(PropertyUtils.getProperty(obj, propertyName));
                }
            } catch (Exception e) {
                throw Reflections.convertReflectionExceptionToUnchecked(e);
            }

            return list;
        }

        /**
         * ????(Getter), ??.
         * 
         * @param collection ???.
         * @param propertyName ??????.
         * @param separator .
         */
        public static String extractToString(final Collection collection, final String propertyName,
                final String separator) {
            List list = extractToList(collection, propertyName);
            return StringUtils.join(list, separator);
        }

        /**
         * ?Collection(toString())String,  separator
         */
        public static String convertToString(final Collection collection, final String separator) {
            return StringUtils.join(collection, separator);
        }

        /**
         * ?Collection(toString())String, ???prefix??postfix<div>mymessage</div>
         */
        public static String convertToString(final Collection collection, final String prefix, final String postfix) {
            StringBuilder builder = new StringBuilder();
            for (Object o : collection) {
                builder.append(prefix).append(o).append(postfix);
            }
            return builder.toString();
        }

        /**
         * ?.
         */
        public static boolean isEmpty(Collection collection) {
            return (collection == null) || collection.isEmpty();
        }

        /**
         * ?.
         */
        public static boolean isEmpty(Map map) {
            return (map == null) || map.isEmpty();
        }

        /**
         * ?.
         */
        public static boolean isNotEmpty(Collection collection) {
            return (collection != null) && !(collection.isEmpty());
        }

        /**
         * ?Collectioncollectionnull.
         */
        public static <T> T getFirst(Collection<T> collection) {
            if (isEmpty(collection)) {
                return null;
            }

            return collection.iterator().next();
        }

        /**
         * ?Collection? collectionnull.
         */
        public static <T> T getLast(Collection<T> collection) {
            if (isEmpty(collection)) {
                return null;
            }

            // List?? 
            if (collection instanceof List) {
                List<T> list = (List<T>) collection;
                return list.get(list.size() - 1);
            }

            // iterator?.
            Iterator<T> iterator = collection.iterator();
            while (true) {
                T current = iterator.next();
                if (!iterator.hasNext()) {
                    return current;
                }
            }
        }

        /**
         * a+bList.
         */
        public static <T> List<T> union(final Collection<T> a, final Collection<T> b) {
            List<T> result = new ArrayList<T>(a);
            result.addAll(b);
            return result;
        }

        /**
         * a-bList.
         */
        public static <T> List<T> subtract(final Collection<T> a, final Collection<T> b) {
            List<T> list = new ArrayList<T>(a);
            for (T element : b) {
                list.remove(element);
            }

            return list;
        }

        /**
         * abList.
         */
        public static <T> List<T> intersection(Collection<T> a, Collection<T> b) {
            List<T> list = new ArrayList<T>();

            for (T element : a) {
                if (b.contains(element)) {
                    list.add(element);
                }
            }
            return list;
        }
    }