我对 Lambda 和流有点陌生。经过大量研究，我找不到解决我的问题的正确答案。但如果你知道任何相关答案，请给我链接，我会删除这个问题。谢谢。
我的问题是我尝试将以下代码转换为 Lambda。但因为我在嵌套循环中使用索引和验证，所以我无法使用 Lambda 将其转换为一个 block 代码(可能吗？)。 另外，如果有人提出以更好的方式编写此代码的建议，我将不胜感激。
for (int i = 0; i < list1.length(); i++) {
if (list1.getJSONObject(i).has("owner")) {
dataObject1 = list1.getJSONObject(i).getJSONObject("owner");
if (GeneralUtils.isNameExist(inputNameOrSubject, dataObject1, true)) {
if (usersList != null) {
for (int j = 0; j < usersList.length(); j++) {
if (
GeneralUtils.isNameExist(usersList.getJSONObject(j).getString("first_name"), dataObject1, false) ||
GeneralUtils.isNameExist(usersList.getJSONObject(j).getString("last_name"), dataObject1, false)
) {
usersExist = true;
usersIndex = j;
}
}
if (usersExist) {
if (list1.getJSONObject(i).has("name")) {
topicName = list1.getJSONObject(i).getString("name");
topicListJA = usersList.getJSONObject(usersIndex).getJSONArray("topics");
topicExist = false;
for (int t = 0; t < topicListJA.length(); t++) {
if (topicName.toLowerCase().equals(topicListJA.getString(t).toLowerCase())) {
topicExist = true;
break;
}
}
if (!topicExist) {
usersList.getJSONObject(usersIndex).getJSONArray("topics").put(topicName);
}
}
} else {
result = dataObject1;
result.put("topics", new JSONArray(new String[]{list1.getJSONObject(i).getString("name")}));
usersList.put(result);
}
} else if (list1.getJSONObject(i).has("name")) {
result = dataObject1;
result.put("topics", new JSONArray(new String[]{list1.getJSONObject(i).getString("name")}));
usersList = new JSONArray();
usersList.put(result);
}
}
}
}
return String.valueOf(usersList);
更新: 输入列表是一个 JSON 数组，如下所示:
[{
owner: {
signature: "",
created: "2019-08-26 02:14:15",
nickname: "",
last_name: "Kennedy",
title: null,
first_name: "Victor",
updated: "2019-11-24 20:58:57",
email: "v.kennedy@gmail.com"
},
topics: [
{
id:"0"
name: "topic 1"
},{
id:"1"
name: "topic 2"
},{
id:"0"
name: "topic 3"
},
]
},
{ owner: {
signature: "",
created: "2014-03-25 23:51:48",
nickname: "",
last_name: "Kent",
title: "",
first_name: "Bill",
updated: "2019-11-21 21:26:24",
email: "bill.kent@gmail.com"
},
topics: [
{
id:"0"
name: "topic 6"
},{
id:"1"
name: "topic 7"
},{
id:"0"
name: "topic 8"
},
]
} ,
{
owner: {
signature: "",
created: "2014-03-25 23:51:48",
nickname: "",
last_name: "Novel",
title: "",
first_name: "Tim",
updated: "2019-10-21 21:26:24",
email: "tim.novel@gmail.com"
}
,
topics: [
{
id:"0"
name: "topic 16"
},{
id:"1"
name: "topic 17"
},{
id:"0"
name: "topic 18"
},
]
},
{ owner: {
signature: "",
created: "2014-03-25 23:51:48",
nickname: "",
last_name: "Kent",
title: "",
first_name: "Bill",
updated: "2019-11-21 21:26:24",
email: "bill.kent@gmail.com"
},
topics: [
{
id:"0"
name: "topic 36"
},{
id:"1"
name: "topic 37"
},{
id:"0"
name: "topic 38"
},
]
}
]
当 API 收到关键字“ken”作为名称时，我需要发回前两个 JSON 对象和最后一个，其中包含主题值的组合详细信息(我的意思是 Bill Kent 的一个 JSON 对象和组合主题:6 ,7,8,36,37,38) 作为回应!
最佳答案
我必须先提一下，您的 JSON 字符串无效。因为所有键都必须用双引号括起来，并且属于同一 JSON 数组的所有 JSON 节点必须用逗号分隔。
以下代码片段显示了实现您想要的效果的另一种方法。首先使用Map与 first_name和last_name由 & 连接作为键，然后组合 topics key 相同的 JSON 节点。最后转换Map到一个新的 JSON 节点。顺便说一句，Jackson (最流行的 JSON 库之一)被引入来演示这一点。
代码片段
ObjectMapper mapper = new ObjectMapper();
ArrayNode root = (ArrayNode) mapper.readTree(jsonStr);
Map<String, JsonNode> rootMap = new HashMap<>();
root.forEach(e -> {
String firstName = e.get("owner").get("first_name").toString().toLowerCase();
String lastName = e.get("owner").get("last_name").toString().toLowerCase();
if (firstName.contains("ken") || lastName.contains("ken")) {
String key = String.format("%s&%s", firstName, lastName);
if (rootMap.containsKey(key)) {
e.get("topics").forEach(e1 -> {
((ArrayNode) rootMap.get(key).get("topics")).add(e1);
});
} else {
rootMap.put(key, e);
}
}
});
ArrayNode rootNew = mapper.createArrayNode();
rootMap.forEach((k,v) -> {
rootNew.add(v);
});
System.out.println(rootNew.toString());
控制台输出
[
{
"owner":{
"signature":"",
"created":"2014-03-25 23:51:48",
"nickname":"",
"last_name":"Kent",
"title":"",
"first_name":"Bill",
"updated":"2019-11-21 21:26:24",
"email":"bill.kent@gmail.com"
},
"topics":[
{
"id":"0",
"name":"topic 6"
},
{
"id":"1",
"name":"topic 7"
},
{
"id":"0",
"name":"topic 8"
},
{
"id":"0",
"name":"topic 36"
},
{
"id":"1",
"name":"topic 37"
},
{
"id":"0",
"name":"topic 38"
}
]
},
{
"owner":{
"signature":"",
"created":"2019-08-26 02:14:15",
"nickname":"",
"last_name":"Kennedy",
"title":"null",
"first_name":"Victor",
"updated":"2019-11-24 20:58:57",
"email":"v.kennedy@gmail.com"
},
"topics":[
{
"id":"0",
"name":"topic 1"
},
{
"id":"1",
"name":"topic 2"
},
{
"id":"0",
"name":"topic 3"
}
]
}
]
更新
给你!您可以使用 org.json 获得相同的结果如下:
JSONArray root = new JSONArray(jsonStr);
Map<String, JSONObject> rootMap = new HashMap<>();
for (int i = 0; i < root.length(); i++) {
JSONObject obj = root.getJSONObject(i);
String firstName = obj.getJSONObject("owner").getString("first_name").toLowerCase();
String lastName = obj.getJSONObject("owner").getString("last_name").toLowerCase();
if (firstName.contains("ken") || lastName.contains("ken")) {
String key = String.format("%s&%s", firstName, lastName);
if (rootMap.containsKey(key)) {
obj.getJSONArray("topics").forEach(e1 -> {
rootMap.get(key).getJSONArray("topics").put(e1);
});
} else {
rootMap.put(key, obj);
}
}
}
JSONArray rootNew = new JSONArray();
rootMap.forEach((k,v) -> {
rootNew.put(v);
});
System.out.println(rootNew.toString());
关于java - 使用 Lambda、Stream java 将值添加到两个嵌套的 JSON 数组中，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/59131175/