java - 将 JSON 对象数组转换为列表

Question

我有一段 JSON 格式的选择数据，我想将其转换为 Java ArrayList。

String q = "SELECT attributes FROM common_attr_test";
PreparedStatement preparedStatement = (PreparedStatement) conn.prepareStatement(q);
preparedStatement.execute();
ResultSet rs = preparedStatement.executeQuery();
while (rs.next()) {
    valueAttributes = rs.getString("attributes");
} 

JSONObject obj=(JSONObject)JSONValue.parse(valueAttributes); 
JSONArray arrOne=(JSONArray)obj.get("1"); 
System.out.println(arrOne);

从代码中，我得到以下结果:

[{"entry":"1","count":1},{"entry":"2","count":1},{"entry":"3","count":1}]

我尝试使用

进行编码

ArrayList<String> listOne = new ArrayList<String>();

if (arrOne != null) { 
    int len = arrOne.size();
    for (int i=0;i<len;i++){ 
        listOne.add(arrOne.get(i).toString());
    } 
} 
System.out.println(arrOne);
System.out.println("\nlistOne:"+listOne);

并得到结果:

[{"entry":"2","count":3}]

我的问题是如何将结果放入 Java 中的 ArrayList 中，如下所示:

[(1,1),(2,1),(3,1)]

Answer 1

您需要检查 JSONArray，将每个元素转换为 JSONObject 并提取 entry 和 count值，然后用它们创建一个字符串并添加到您的列表中:

if (arrOne != null) {
    JSONObject entryCountJson;
    String entry, count;
    for (Object o : arrOne) {
        entryCountJson = (JSONObject) o;
        entry = String.valueOf(entryCountJson.get("entry"));
        count = String.valueOf(entryCountJson.get("count"));
        listOne.add("(" + entry + "," + count + ")");
    }
}
System.out.println("arrOne: "+arrOne);
System.out.println("listOne: "+listOne);

输出:

arrOne: [{"entry":"1","count":1},{"entry":"2","count":1},{"entry":"3","count":1}]
listOne: [(1,1), (2,1), (3,1)]