java list gson,Gson无法将字符串值转换为List，Java

心已赠人 2023-01-24 04:22 256阅读 0赞

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I thought that Im strong enough to play with Gson but I found some problem.

I have String that I need to convert to Object. The String is generated from some xml.

Here is example of 1st one:

"ClientData": \{

"pixelList": \{

"pixel": \[\{

"b": 22,

"a": 1234

\},

"b": 33,

"a": 34344

\}\]

Seems simple, right?

So I created followed classes and succeeded to convert above mentioned String to Java Object.

public class ClientDataRoot \{

@SerializedName("ClientData") ClientData clientData = null;

public class ClientData \{

PixelList pixelList = null;

public class PixelList \{

List pixel = null;

public class Pixel \{

private String a = "";

private String b = "";

From 1st example you can see that pixelList has 2 objects: pixel.

But what happens if you get pixelList with one pixel:

2nd one:

"ClientData": \{

"pixelList": \{

"pixel": \{

"b": 22,

"a": 1234

Here I get the error:

com.google.gson.JsonParseException: The JsonDeserializer

com.google.gson.DefaultTypeAdapters$CollectionTypeAdapter@d1918a failed to deserialize

json object \{"b":22,"a":1234\} given the type java.util.List

My code is simple:

import com.google.gson.Gson;

....

Gson gson = new Gson();

ClientDataRoot clientDataRoot1 =

gson.fromJson(xmlJSONObj.toString(), ClientDataRoot.class);

I use gson-1.7.1.jar

BTW if I change class PixelList from

public class PixelList \{

List pixel = null;

to:

public class PixelList \{

Pixel pixel = null;

It works, but I need it as List

Thank you,

How to Fix it:

As guys say when I try to convert XML to JSON, the plugin converts pixel to JSONObjext instead JSONArray.

Here is a code I fixed my problem:

// responseBody is XML String

JSONObject xmlJSONObj = XML.toJSONObject(responseBody);

JSONObject cd = (JSONObject) xmlJSONObj.get("ClientData");

JSONObject pl = (JSONObject) cd.get("pixelList");

Object p = pl.get("pixel");

if (p instanceof JSONObject) \{

JSONArray arr = new JSONArray();

arr.put(p);

pl.remove("pixel");

pl.put("pixel", arr);

Thanks to PeterMmm and R.J

解决方案

That is because either the JSON returning third party is returning a wrong JSON, or if you're generating the JSON yourself, you're doing it wrongly. A single element in pixelList should have a JSON that would look like this:-

"clientData": \{

"pixelList": \{

"pixel": \[

"a": "22",

"b": "1234"

Either the JSON needs to be corrected or else, you can do something like this. Have 2 objects, 1 of the type1(one which parses a list) and the other of type2(one which parses a single element json).

Now parse the json with type1 class and keep it in a try-catch. If you get this Exception, catch it and parse it with the type2 class. This seems to be the only workaround, if you can't get the JSON response fixed.

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