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  • 封装一个按Key排序的Map工具

    Map是集合的存放顺序是按哈希值定的,有时候不是我们需要的,当想要一个按自己规定顺序存放顺序,可以用LinkedHashMap,这里自己把LinkedHashMap封装了一次

    package test.com.reflect;
    
    import java.util.Arrays;
    import java.util.Collections;
    import java.util.Comparator;
    import java.util.HashMap;
    import java.util.HashSet;
    import java.util.LinkedHashMap;
    import java.util.List;
    import java.util.Map;
    import java.util.Set;
    import java.util.TreeSet;
    
    
    public class MapUtill {
        public static void main(String[] args) {
            Map<Object,Object> map1 = newMap("{'id':'主键','age':'年龄','name':'姓名','className':'班级','area':{'code':'代码','name':'地名','as':'的'},'strs':'发大发'} ",true);
            System.err.println(map1);
            // --------------------------------------------------------------------------------
            Map<Integer,String> map = new HashMap<>();
            map.put(2342, "a1");
            map.put(1231, "a2");
            map.put(24355, "a3");
            map.put(123, "a4");
            System.err.println(map);
            // --------------------------------------------------------------------------------
            Object[] arr = sortKeysArray(map,new Comparator<Integer>() {
    
                @Override
                public int compare(Integer o1, Integer o2) {
                    return o1-o2;
                }
    
            });
            System.err.println(Arrays.toString(arr));
            // --------------------------------------------------------------------------------
            Set<Integer> set = sortKeysSet(map,new Comparator<Integer>() {
    
                @Override
                public int compare(Integer o1, Integer o2) {
                    return o1-o2;
                }
    
            });
            System.err.println(set);
            // --------------------------------------------------------------------------------
            List<Integer> list = sortKeysList(map,new Comparator<Integer>() {
    
                @Override
                public int compare(Integer o1, Integer o2) {
                    return o1-o2;
                }
    
            });
            System.err.println(list);
            
        }
        /** 返回一个按添加顺序存放的map
         * @return
         */
        public static <V, K> Map<K,V> newMap(){
            return new LinkedHashMap<K,V>();
        }
        
        public static Map<Object,Object> newMap(String txt){
            return newMap(txt,false);
        }
        
        /**
         * @param txt Map字符串
         * @param sort 是否按txt 排序生成
         * @return
         */
        @SuppressWarnings({ "unchecked", "rawtypes" })
        public static  Map<Object,Object> newMap(String txt,Boolean sort){
            com.alibaba.fastjson.JSONObject jsonObj = com.alibaba.fastjson.JSONObject.parseObject(txt);
            if(!sort) {
                return (Map)jsonObj;
            }
            final String  t = txt;
    //        Map<String, Object> rs = sort(jsonObj,new Comparator<String>() {
    //            @Override
    //            public int compare(String o1, String o2) {
    //                if(t.indexOf(o1)> t.indexOf(o2)) {
    //                    return 1;
    //                }
    //                if(t.indexOf(o1)< t.indexOf(o2)) {
    //                    return -1;
    //                }
    //                return 0;
    //            }
    //        });
            
            Object[] arrKeys = sortKeysArray((Map)jsonObj,new Comparator<String>() {
                @Override
                public int compare(String o1, String o2) {
                    if(t.indexOf(o1)> t.indexOf(o2)) {
                        return 1;
                    }
                    if(t.indexOf(o1)< t.indexOf(o2)) {
                        return -1;
                    }
                    return 0;
                }
            });
            
            Map<String, Object> rs = newMap();
            for (int i = 0; i < arrKeys.length; i++) {
                Object v = jsonObj.get(arrKeys[i]);
                if(v instanceof Map) {
                    int key = txt.indexOf((String)arrKeys[i]);
                    int  index1 = txt.indexOf("{", key);
                    int  index2 = txt.indexOf("}", index1);
                    v = newMap(txt.substring(index1,index2+1),false);
                }
                rs.put((String)arrKeys[i], v);
            }
            return (Map)rs;
        }
        
        /**
         * @param map
         * @param comparator
         * @return
         */
        public static  <K, V> Map<K,V> sort(Map<K,V> map,Comparator<K> comparator){
            Map<K, V> rs = newMap();
            K[] arrKeys = sortKeysArray(map,comparator);
            for (K k : arrKeys) {
                rs.put(k, map.get(k));
            }
            return rs;
        }
        
        /**
         * @param map
         * @param comparator
         * @return Object[] 不能用K[] 来接收
         */
        @SuppressWarnings("unchecked")
        public  static <K, V> K[] sortKeysArray(Map<K,V> map,Comparator<K> comparator) {
            Set<K> keys = map.keySet();
            K[] arr = (K[])(new Object[keys.size()]);
            K[] arrKeys = keys.toArray(arr);
            Arrays.sort(arrKeys,comparator);
            return arr;
        }
        /**
         * @param map
         * @param comparator
         * @return
         */
        public  static <K, V> Set<K> sortKeysSet(Map<K,V> map,Comparator<K> comparator) {
            return new TreeSet<>(sortKeysList(map,comparator));
        }
        
        /**
         * @param map
         * @param comparator
         * @return
         */
        public  static <K, V> List<K> sortKeysList(Map<K,V> map,Comparator<K> comparator) {
            K[] keys = sortKeysArray(map,comparator);
            return Arrays.asList(keys);
        }
    }
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  • 原文地址:https://www.cnblogs.com/jonrain0625/p/11191516.html
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