Android:对从 SharedPreferences 检索到的数据进行排序 [英] Android: Sort data retrieved from SharedPreferences

问题描述

我正在尝试在 Android 中存储数据.我正在使用 SharedPreferences.我正在使用以下方法检索这些数据:

I am trying to store data in Android. I am using the SharedPreferences. And I am retrieving these data by using:

 SharedPreferences myPrefs = this.getSharedPreferences("myPrefs", MODE_WORLD_READABLE);
            Map<String, ?> keys = myPrefs.getAll();
            for (Map.Entry<String, ?> entry : keys.entrySet()) {
                Log.i("map values", entry.getKey());
                            //some code
 }

但是检索到的数据与插入的顺序不同.如何获得相同的订单?

But data retrieved are not in the same order as they were inserted. How to get the same order?

推荐答案

将生成的 Map 复制到 SortedMap 的实现中，例如TreeMap.

Copy the resulting Map into an implementation of SortedMap, e.g. TreeMap.

像这样(按键排序):

SharedPreferences myPrefs = this.getSharedPreferences("myPrefs", MODE_WORLD_READABLE);
TreeMap<String, ?> keys = new TreeMap<String, Object>(myPrefs.getAll());
for (Map.Entry<String, ?> entry : keys.entrySet()) {
    Log.i("map values", entry.getKey());
    //some code
}

按值排序&不要丢失任何键值对(因为 Map 很容易允许将重复值映射到不同的键)，您需要先将其转换为一个 List 并对其进行排序.

To sort by value & not lose any key-value pairs (since a Map will readily allow duplicate values mapping to different keys) you'd need to first convert it into a List and sort that.

    List<Pair<Object, String>> sortedByValue = new LinkedList<Pair<Object,String>>();
    for (Map.Entry<String, ?> entry : keys.entrySet()) {
        Pair<Object, String> e = new Pair<Object, String>(entry.getValue(), entry.getKey());
        sortedByValue.add(e);
    }

    // Pair doesn't have a comparator, so you're going to need to write one.
    Collections.sort(sortedByValue, new Comparator<Pair<Object, String>>() {
        public int compare(Pair<Object, String> lhs, Pair<Object, String> rhs) {
            // This is a naive and shitty comparator, but it works for
            // arbitrary objects. Sort of. Tweak depending on the order you need.
            String sls = String.valueOf(lhs.first);
            String srs = String.valueOf(rhs.first);
            int res = sls.compareTo(srs);
            // Sort on value first, key second
            return res == 0 ? lhs.second.compareTo(rhs.second) : res;
        }
    });

    for (Pair<Object, String> pair : sortedByValue) {
        Log.i("map values", pair.first + "/" + pair.second);
    }

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