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Sort by a field in jsonArray

2022-07-29 22:44:00 【51CTO】

在一些业务场景中,我们需要对一些jsonArray to pressjsonSort by the size of a field in the array,例如这段json

       
       {
       
       "name":
       
       "网站",
       
       "num":
       
       3,
       
       "sites": [
       
        { 
       
       "name":
       
       "Google", 
       
       "info":[ 
       
       "Android", 
       
       "Google 搜索", 
       
       "Google 翻译" ] },
       
        { 
       
       "name":
       
       "Runoob", 
       
       "info":[ 
       
       "菜鸟教程", 
       
       "菜鸟工具", 
       
       "菜鸟微信" ] },
       
        { 
       
       "name":
       
       "Taobao", 
       
       "info":[ 
       
       "淘宝", 
       
       "网购" ] }
       
    ]
       
}
      
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Now the business requires us to basejson数组sites中的name字段排序,我们应该怎么做呢？

       
       /**
       
       * 对json数组排序,
       
       * @param jsonArr
       
       * @param sortKey 排序关键字
       
       * @param is_desc is_desc-false升序列 is_desc-true降序 (排序字段为字符串)
       
       * @return
       
       */
       
       public 
       
       static 
       
       String 
       
       jsonArraySort(
       
       JSONArray 
       
       jsonArr,
       
       String 
       
       sortKey,
       
       boolean 
       
       is_desc) {
       
       //存放排序结果json数组
       
       JSONArray 
       
       sortedJsonArray 
       
       = 
       
       new 
       
       JSONArray();
       
       //用于排序的list
       
       List
       
       <
       
       JSONObject
       
       > 
       
       jsonValues 
       
       = 
       
       new 
       
       ArrayList
       
       <
       
       JSONObject
       
       >();
       
       //将参数jsonExtract each item of the array,放入list
       
       for (
       
       int 
       
       i 
       
       = 
       
       0; 
       
       i 
       
       < 
       
       jsonArr.
       
       size(); 
       
       i
       
       ++) {
       
       jsonValues.
       
       add(
       
       JSONObject.
       
       fromObject(
       
       jsonArr.
       
       getJSONObject(
       
       i)));
       
        }
       
       //快速排序,重写compare方法,Completes the comparison by the specified field,完成排序
       
       Collections.
       
       sort(
       
       jsonValues, 
       
       new 
       
       Comparator
       
       <
       
       JSONObject
       
       >() {
       
       //排序字段
       
       private  
       
       final 
       
       String 
       
       KEY_NAME 
       
       = 
       
       sortKey;
       
       //重写compare方法
       
       @Override
       
       public 
       
       int 
       
       compare(
       
       JSONObject 
       
       a, 
       
       JSONObject 
       
       b) {
       
       String 
       
       valA 
       
       = 
       
       new 
       
       String();
       
       String 
       
       valB 
       
       = 
       
       new 
       
       String();
       
       try {
       
       valA 
       
       = 
       
       a.
       
       getString(
       
       KEY_NAME);
       
       valB 
       
       = 
       
       b.
       
       getString(
       
       KEY_NAME);
       
                } 
       
       catch (
       
       JSONException 
       
       e) {
       
       e.
       
       printStackTrace();
       
                }
       
       //是升序还是降序
       
       if (
       
       is_desc){
       
       return 
       
       -
       
       valA.
       
       compareTo(
       
       valB);
       
                } 
       
       else {
       
       return 
       
       -
       
       valB.
       
       compareTo(
       
       valA);
       
                }
       
            }
       
        });
       
       //Put the sorted result into the resultjsonArray
       
       for (
       
       int 
       
       i 
       
       = 
       
       0; 
       
       i 
       
       < 
       
       jsonArr.
       
       size(); 
       
       i
       
       ++) {
       
       sortedJsonArray.
       
       add(
       
       jsonValues.
       
       get(
       
       i));
       
        }
       
       return 
       
       sortedJsonArray.
       
       toString();
       
    }
      
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补充：

在java中有两个比较器

java.lang.Comparable接口

       
       public 
       
       interface 
       
       Comparable
       
       <
       
       T
       
       > {
       
       public 
       
       int 
       
       compareTo(
       
       T 
       
       o);
       
}
      
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java.util.Comparator 接口

       
       public 
       
       interface 
       
       Comparator
       
       <
       
       T
       
       > {
       
       int 
       
       compare(
       
       T 
       
       o1, 
       
       T 
       
       o2);
       
       //省略...........
       
 }
      
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两种比较器的区别：

java.lang.ComparableWhat is supported is an intra-comparison,What is internal comparison：That is, the foreign object and the current objectthis的比较

java.util.ComparatorWhat is supported is an external comparison,What is external comparison,That is, the comparison of two outer objects is supported,Comparison with the current object is not supported

原网站

版权声明
本文为[51CTO]所创，转载请带上原文链接，感谢
https://yzsam.com/2022/210/202207292133073482.html

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Sort by a field in jsonArray

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