用Java对LinkedHashMap进行排序

本文介绍了用Java对LinkedHashMap进行排序的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

我想按值对HashMap进行排序. 我目前正在使用以下代码

I want to sort a HashMap by values. I'm currently using the following code

public static Map<String, Float> sortByValue(Map<String, Float> unsorted_map){ Map<String, Float> sorted_map = new LinkedHashMap<String, Float>(); try{ // 1. Convert Map to List of Map List<Map.Entry<String, Float>> list = new LinkedList<Map.Entry<String, Float>>(unsorted_map.entrySet()); // 2. Sort list with Collections.sort(), provide a custom Comparator Collections.sort(list, new Comparator<Map.Entry<String, Float>>() { public int compare(Map.Entry<String, Float> o1, Map.Entry<String, Float> o2) { return (o1.getValue())pareTo(o2.getValue()); } }); // 3. Loop the sorted list and put it into a new insertion order Map LinkedHashMap for (Map.Entry<String, Float> entry : list) { sorted_map.put(entry.getKey(), entry.getValue()); } } catch(Exception e){ e.printStackTrace(); } return sorted_map; }

但是输出错误. 特别是，值以降序开始，然后在0.0值之后按升序排列(如第二个数据列所示).

but the output is wrong. In particular, values begin in descending order then, after a 0.0 value, they become in ascending order (as the second data column shows).

---> 1985 0.54660827 ---> 2002 0.45290402 ---> 1993 0.40605184 ---> 2015 0.3591997 ---> 2000 0.34358233 ---> 1980 0.2811128 ---> 2008 0.24987808 ---> 1990 0.23426071 ---> 1983 0.23426071 ---> 1986 0.21864335 ---> 1977 0.18740855 ---> 1992 0.1717912 ---> 2009 0.14055647 ---> 2006 0.12493904 ---> 2011 0.031234872 ---> 2001 0.015617436 ---> 1975 0.0 ---> 1997 0.031234723 ---> 2004 0.046852008 ---> 1988 0.062469445 ---> 2013 0.07808688 ---> 1978 0.07808688 ---> 2005 0.1093216 ---> 1981 0.14055632 ---> 1976 0.14055632 ---> 2014 0.14055632 ---> 1999 0.15617377 ---> 1994 0.20302577 ---> 1987 0.20302577 ---> 2010 0.2186432 ---> 1991 0.24987794 ---> 1989 0.24987794 ---> 1996 0.28111264 ---> 2012 0.28111264 ---> 2003 0.29673007 ---> 1998 0.29673007 ---> 2007 0.31234753 ---> 1984 0.3904344 ---> 1982 0.42166913 ---> 1979 0.5309907 ---> 1995 0.73401666

有人可以帮助我吗?

提前谢谢！

推荐答案

我认为您的代码应该可以工作.我像您一样编写代码，并且可以正常工作，这是我的代码

I think your code some should works. i write code like you and it works, here is my code

public static void main(String[] args) { Map<Integer, Float> unsortFloatMap = new HashMap<Integer, Float>(); unsortFloatMap.put(1985, 0.54660827f); unsortFloatMap.put(2002, 0.45290402f); unsortFloatMap.put(1993, 0.40605184f); unsortFloatMap.put(2015, 0.3591997f); unsortFloatMap.put(1975, 0.0f); unsortFloatMap.put(1997, 0.031234723f); unsortFloatMap.put(2004, 0.046852008f); unsortFloatMap.put(2005, 0.1093216f); unsortFloatMap.put(2003, 0.29673007f); unsortFloatMap.put(1998, 0.29673007f); unsortFloatMap.put(2007, 0.31234753f); unsortFloatMap.put(1995, 0.73401666f); System.out.println("Unsort Float Map......"); printMap(unsortFloatMap); System.out.println("Sorted Float Map......"); Map<Integer, Float> sortedFloatMap = sortByFloatValue(unsortFloatMap); printMap(sortedFloatMap); } // pretty print a map public static <K, V> void printMap(Map<K, V> map) { for (Map.Entry<K, V> entry : map.entrySet()) { System.out.println("Key : " + entry.getKey() + " Value : " + entry.getValue()); } } private static Map<Integer, Float> sortByFloatValue(Map<Integer, Float> unsortMap) { List<Map.Entry<Integer, Float>> list = new LinkedList<Map.Entry<Integer, Float>>(unsortMap.entrySet()); Collections.sort(list, new Comparator<Map.Entry<Integer, Float>>() { public int compare(Map.Entry<Integer, Float> o1, Map.Entry<Integer, Float> o2) { return (o1.getValue())pareTo(o2.getValue()); } }); /// Loop the sorted list and put it into a new insertion order Map /// LinkedHashMap Map<Integer, Float> sortedMap = new LinkedHashMap<Integer, Float>(); for (Map.Entry<Integer, Float> entry : list) { sortedMap.put(entry.getKey(), entry.getValue()); } return sortedMap; }

输出为:

Unsort Float Map...... Key : 2002 Value : 0.45290402 Key : 2003 Value : 0.29673007 Key : 1985 Value : 0.54660827 Key : 1975 Value : 0.0 Key : 2007 Value : 0.31234753 Key : 2004 Value : 0.046852008 Key : 2005 Value : 0.1093216 Key : 1995 Value : 0.73401666 Key : 1993 Value : 0.40605184 Key : 1998 Value : 0.29673007 Key : 2015 Value : 0.3591997 Key : 1997 Value : 0.031234723 Sorted Float Map...... Key : 1975 Value : 0.0 Key : 1997 Value : 0.031234723 Key : 2004 Value : 0.046852008 Key : 2005 Value : 0.1093216 Key : 2003 Value : 0.29673007 Key : 1998 Value : 0.29673007 Key : 2007 Value : 0.31234753 Key : 2015 Value : 0.3591997 Key : 1993 Value : 0.40605184