循环获取JAVA中JSONObject内的相同对象N次

Question

如何将此响应解析为ArrayList。我有一个包含对象列表的层次结构数组，在每个对象中，当我得到类型时；组"；则将CCD_ 2作为"0"；内容"；，在JSONArray中，我可以得到n个对象。每个对象可以包含类型为"；组"；。如何解析并保存在ArrayList中。

hierarchy: 
[
{
"id":"5fd1b4384f5ee9964099b6b0",
"name":"Dev_5 Category Group `",
"type":"group",
"contents":[
{
"id":"5fd1b4384f5ee9964099b6af",
"name":"Dev_5 Parent Category Group 1",
"type":"group",
"contents":[
{
"id":"5fd1b567505ee9af3a7a65c8",
"name":"Dev_5 Parent Category Group 2",
"type":"group",
"contents":[
{
"id":"5fd1b4384f5ee9964099b6b1",
"type":"category"
}
],
"desc":"",
"image":""
}
],
"desc":"",
"image":""
},
{
"id":"5fd1b57b4f5ee9114599b679",
"type":"category"
}
],
"desc":"",
"image":""
},
{
----
},
{
---
}
]

代码

for (int i = 0; i < hierarchyArray.length(); i++) 
{ 
hierarchyItemList.clear(); 
JSONObject obj = hierarchyArray.optJSONObject(i); 
JSONArray contentArray = obj.optJSONArray("contents"); 
HierarchyItem item = new HierarchyItem(); 
item.setId(obj.optString("id")); 
item.setType(obj.optString("type")); 
item.setGroupName(obj.optString("name")); 
if (obj.optString("type").equalsIgnoreCase("group") && contentArray != null && 
contentArray.length() > 0) { 
hierarchyItemList.clear(); 
for (int j = 0; j < contentArray.length(); j++) 
{ 
hierarchyItemList.add(MenuJSON.hierarchyJSON(contentArray.optJSONObject(j))); 
} 
item.setContentList(hierarchyItemList); 
} 
if (obj.optString("type").equalsIgnoreCase("category") || 
(obj.optString("type").equalsIgnoreCase("group") && contentArray != null && 
contentArray.length() > 0)) { 
itemList.add(item); 
}
}
private static HierarchyItem hierarchyJSON(JSONObject obj) {
HierarchyItem item = new HierarchyItem();
item.setId(obj.optString("id"));
item.setType(obj.optString("type"));
item.setGroupName(obj.optString("name"));
JSONArray contentArray = obj.optJSONArray("contents");
List<HierarchyItem> hierarchyItemList = new ArrayList<>();
if (obj.optString("type").equalsIgnoreCase("group") && contentArray != null && contentArray.length() > 0) {
hierarchyItemList.clear();
for (int j = 0; j < contentArray.length(); j++) {
hierarchyItemList.add(MenuJSON.hierarchyJSON(contentArray.optJSONObject(j)));
}
item.setContentList(hierarchyItemList);
}
return item;
}

使用上面的代码，最后一个项目将更新为ArrayList中的所有项目。如何解决此问题。提前谢谢。

Answer 1

您已经清除了每个循环中的值列表，因此现有数据将被清除，新值将在列表中更新，就像您使用递归循环一样。我已经删除了list值的clear((，并在循环开始时再次初始化。这将解决您的问题。

for (int i = 0; i < hierarchyArray.length(); i++) 
{

//hierarchyItemList.clear(); --> Remove this clear() method, it will clear your existing values
JSONObject obj = hierarchyArray.optJSONObject(i); 
JSONArray contentArray = obj.optJSONArray("contents"); 
HierarchyItem item = new HierarchyItem(); 
item.setId(obj.optString("id")); 
item.setType(obj.optString("type")); 
item.setGroupName(obj.optString("name")); 
if (obj.optString("type").equalsIgnoreCase("group") && contentArray != null && 
contentArray.length() > 0) { 
//hierarchyItemList.clear(); 
hierarchyItemList = new ArrayList<>(); // instead of clear the list, initialize it as new list, then it will keep existing list values and load new data in new list
for (int j = 0; j < contentArray.length(); j++) 
{ 
hierarchyItemList.add(MenuJSON.hierarchyJSON(contentArray.optJSONObject(j))); 
} 
item.setContentList(hierarchyItemList); 
} 
if (obj.optString("type").equalsIgnoreCase("category") || 
(obj.optString("type").equalsIgnoreCase("group") && contentArray != null && 
contentArray.length() > 0)) { 
itemList.add(item); 
}
}
private static HierarchyItem hierarchyJSON(JSONObject obj) {
HierarchyItem item = new HierarchyItem();
item.setId(obj.optString("id"));
item.setType(obj.optString("type"));
item.setGroupName(obj.optString("name"));
JSONArray contentArray = obj.optJSONArray("contents");
List<HierarchyItem> hierarchyItemList = new ArrayList<>();
if (obj.optString("type").equalsIgnoreCase("group") && contentArray != null && contentArray.length() > 0) {
hierarchyItemList.clear();
for (int j = 0; j < contentArray.length(); j++) {
hierarchyItemList.add(MenuJSON.hierarchyJSON(contentArray.optJSONObject(j)));
}
item.setContentList(hierarchyItemList);
}
return item;
}

Answer 2

如果hierarchyItemList是您的结果列表，则不应在多个位置清除它，而应仅在最开始时清除它。

这是一个清理版本的

public class JsonDemo {
public static void main(String[] args) throws Exception {
String jsonString = new String(Files.readAllBytes(Paths.get("test.json")), StandardCharsets.UTF_8);
JSONArray hierarchyJsonArray = new JSONArray(jsonString);
List<HierarchyItem> hierarchyItemList = new ArrayList<>();
for(int i = 0; i < hierarchyJsonArray.length(); i++) {
HierarchyItem hierarchyItem = parseItem(hierarchyJsonArray.getJSONObject(i));
hierarchyItemList.add(hierarchyItem);
}
}
private static HierarchyItem parseItem(JSONObject jsonObject) {
HierarchyItem hierarchyItem = new HierarchyItem();
hierarchyItem.id = jsonObject.optString("id", "");
hierarchyItem.type = jsonObject.optString("type", "");
hierarchyItem.name = jsonObject.optString("name", "");
hierarchyItem.desc = jsonObject.optString("desc", "");
hierarchyItem.image = jsonObject.optString("image", "");
// not even checking for type=group, if there is a contents array, parse it
JSONArray contentsArray = jsonObject.optJSONArray("contents");
if(contentsArray != null) {
for(int i = 0; i < contentsArray.length(); i++) {
// recursive call
HierarchyItem childItem = parseItem(contentsArray.getJSONObject(i));
hierarchyItem.contents.add(childItem);
}
}
return hierarchyItem;
}
}
class HierarchyItem {
public String              id       = "";
public String              type     = "";
public String              name     = "";
public String              desc     = "";
public String              image    = "";
public List<HierarchyItem> contents = new ArrayList<>();
}

test.json:

[
{
"id": "5fd1b4384f5ee9964099b6b0",
"name": "Dev_5 Category Group `",
"type": "group",
"contents": [
{
"id": "5fd1b4384f5ee9964099b6af",
"name": "Dev_5 Parent Category Group 1",
"type": "group",
"contents": [
{
"id": "5fd1b567505ee9af3a7a65c8",
"name": "Dev_5 Parent Category Group 2",
"type": "group",
"contents": [
{
"id": "5fd1b4384f5ee9964099b6b1",
"type": "category"
}
],
"desc": "",
"image": ""
}
],
"desc": "",
"image": ""
},
{
"id": "5fd1b57b4f5ee9114599b679",
"type": "category"
}
],
"desc": "",
"image": ""
},
{
"id": "id2",
"type": "category"
},
{
"id": "id3",
"type": "category"
}
]