String jsons = "{'appname':'application', 'Version':'0.1.0', 'UUID':'300V', 'WWXY':'310W', 'ABCD':'270B', 'YUDE':'280T'}";
This is my json string. How can i parse it to GsonBuilder() that i will get object back? I try few thinks but none works.
I also read https://sites.google.com/site/gson/gson-user-guide
public class YourObject {
private String appname;
private String Version;
private String UUID;
private String WWXY;
private String ABCD;
private String YUDE;
//getters/setters
}
parse to Object
YourObject parsed = new Gson().fromJson(jsons, YourObject.class);
or
YourObject parsed = new GsonBuilder().create().fromJson(jsons, YourObject.class);
minor test
String jsons = "{'appname':'application', 'Version':'0.1.0', 'UUID':'300V', 'WWXY':'310W', 'ABCD':'270B', 'YUDE':'280T'}";
YourObject parsed = new Gson().fromJson(jsons, YourObject.class);
works well
EDIT
in this case use JsonParser
JsonObject object = new JsonParser().parse(jsons).getAsJsonObject();
object.get("appname"); // application
object.get("Version"); // 0.1.0
JSON uses double quotes ("), not single ones, for strings so the JSON you have there is invalid. That's likely the cause of any issues you're having converting it to an object.
Related
I am trying to convert a list to Json and sent this json to DB.
My list is as following
List<DeviceInfo> deviceInfoList = [];
class DeviceInfo {
final String platform;
final String deviceModel;
final bool isPhysicalDevice;
final String deviceId;
final String imei;
final String meid;
final String platformVersion;
final String projectVersion;
final String projectCode;
final String projectAppID;
final String projectName;
DeviceInfo(
{this.platform,
this.platformVersion,
this.deviceModel,
this.isPhysicalDevice,
this.deviceId,
this.imei,
this.meid,
this.projectVersion,
this.projectCode,
this.projectAppID,
this.projectName});
}
My list contain String and boolean, I had go through this example don't know how to Map string and bool in that map function.
Can anyone help me with this?
Map<String,dynamic> toJson(){
return {
"name": this.name,
"number": this.number,
"surname": this.surname,
};
}
static List encondeToJson(List<DeviceInfo>list){
List jsonList = List();
list.map((item)=>
jsonList.add(item.toJson())
).toList();
return jsonList;
}
List jsonList = Device.encondeToJson(deviceInfoList);
print("jsonList: ${jsonList}");
Is the most short way that I remember.
Couple of options that will help encoding and decoding from JSON: the json_serializable package is a great way to have the boilerplate serialize/deserialize code generated for you. There's examples of how to use this (and built_value, which is powerful, but more complicated to use) in the Flutter samples repo.
I have a lambda function that accepts a String as an input parameter. When running the lambda function I get the following error:
Can not deserialize instance of java.lang.String out of START_OBJECT token\n
This is what my code too call it looks like:
InvokeRequest request = new InvokeRequest();
final String payload = "";
request.withFunctionName(FUNCTION_NAME).withPayload((String) null);
InvokeResult invokeResult = lambdaClient.invoke(request);
Assert.assertEquals(new String (invokeResult.getPayload().array(), "UTF-8"), "Success");
And this is what my handler looks like:
public String handleRequest(String s, Context context) {}
Now the contents of the string don't matter, it could be null it could be anything. I don't use the input. The obvious solution is to remove it, but because of an annotation generator i'm using I can't do that. I've tried a ByteBuffer input, String, empty String, JSON String {\"s\":\"s\"} but nothing seems to work. I believe I need to pass in a string (i.e no {}). But since I'm using InvokeRequest I don't believe I can do that. Any suggestions would be greatly appreciated.
It works by passing a JSON valid String.
String payload = "{ \"subject\" : \"content\"}";
request.withFunctionName(functionName)
.withPayload(payload);
At the receiving end you have to map it from Object to String again if that's what you want. Here I used Jackson ObjectMapper for this.
ObjectMapper objectMapper = new ObjectMapper();
try {
String payload = objectMapper.writeValueAsString(input);
} catch (JsonProcessingException e) {
e.printStackTrace();
}
I know there are other posts similar to this, but I haven't found any that help me find a solution for this particular case.
I am trying to return a HashMap<String, Object> from my Controller.
The Object part is a JSON string, but its being double serialized and not returned as a raw JSON string, thus not ending up with extra quotations and escape characters.
Controller function:
#RequestMapping(method = RequestMethod.GET, produces = MediaType.APPLICATION_JSON_VALUE)
public HashMap<String, Object> heartbeat(){
String streamInfo = service.getStreamInfo();
String streamCursorInfo = service.getStreamCursorInfo();
String topicInfo = service.getTopicInfo();
String greeting = "This is a sample app for using Spring Boot with MapR Streams.";
HashMap<String, Object> results = new HashMap();
results.put("greeting", greeting);
results.put("streamInfo", streamInfo);
results.put("streamCursorInfo", streamCursorInfo);
results.put("topicInfo", topicInfo);
return results;
}
Service function:
private String performCURL(String[] command){
StringBuilder stringBuilder = new StringBuilder();
try{
ProcessBuilder processBuilder = new ProcessBuilder(command);
Process p = processBuilder.start();
BufferedReader reader = new BufferedReader(new InputStreamReader(p.getInputStream()));
String line = null;
while((line = reader.readLine()) != null){
stringBuilder.append(line);
}
}
catch(Exception e){
LOGGER.error(ExceptionUtils.getRootCauseMessage(e));
}
return stringBuilder.toString();
}
The cURL command I run already returns a raw JSON string. So im just trying to add it to the HashMap to be returned in the heartbeat response.
But every time I run this, my output looks like:
{
"greeting": "This is a sample app for using Spring Boot with MapR Streams.",
"streamCursorInfo": "{\"timestamp\":1538676344564,\"timeofday\":\"2018-10-04 02:05:44.564 GMT-0400 PM\",\"status\":\"OK\",\"total\":1,\"data\":[{\"consumergroup\":\"MapRDBConsumerGroup\",\"topic\":\"weightTags\",\"partitionid\":\"0\",\"produceroffset\":\"44707\",\"committedoffset\":\"10001\",\"producertimestamp\":\"2018-10-03T05:57:27.128-0400 PM\",\"consumertimestamp\":\"2018-09-21T12:35:51.654-0400 PM\",\"consumerlagmillis\":\"1056095474\"}]}",
...
}
If i return only the single string, such as streamInfo then it works fine and doesnt add the extra quotes and escape chars.
Can anyone explain what im missing or need to do to prevent this double serialization?
Instead of returning a HashMap, create an object like this:
public class HeartbeatResult {
private String greeting;
... //other fields here
#JsonRawValue
private String streamCursorInfo;
... //getters and setters here (or make the object immutable by having just a constructor and getters)
}
With #JsonRawValue Jackson will serialize the string as is. See https://www.baeldung.com/jackson-annotations for more info.
streamCursorInfo is a string, not an object => the serialization will escape the " character.
If you are able to return the object containing the data, it will work out of the box. If what you have is just a String, I suggest to serialize it to JsonNode and add it in your response
ObjectMapper objectMapper = new ObjectMapper();
JsonNode streamCursorInfo = objectMapper.readTree(service.getStreamInfo())
results.put("streamCursorInfo", streamCursorInfo);
I created json using Jackson. It is working fine. But while parsing json using jackson i had issues in Escaping trademark symbol. can any one please suggest me how to do escape in json jackson provided library.
Thanks in advance.
Well, basically you don't have to do that. I have written a small test case to show you what I mean:
public class JsonTest {
public static class Pojo {
private final String value;
#JsonCreator
public Pojo(#JsonProperty("value") final String value) {
this.value = value;
}
public String getValue() {
return value;
}
}
#Test
public void testRoundtrip() throws IOException {
final ObjectMapper objectMapper = new ObjectMapper();
final String value = "foo ™ bar";
final String serialized = objectMapper.writeValueAsString(new Pojo(value));
final Pojo deserialized = objectMapper.readValue(serialized, Pojo.class);
Assert.assertEquals(value, deserialized.getValue());
}
}
The above illustrates that the trademark symbol can be serialized and deserialized without escaping.
With that being said, to solve your problem make sure that you are reading the input using the correct encoding. The encoding can e.g. be set when opening the URL or opening the file
BufferedReader urlReader = new BufferedReader(
new InputStreamReader(
url.openStream(), "UTF-8"));
BufferedReader in = new BufferedReader(
new InputStreamReader(
new FileInputStream(file), "UTF-8"));
Also, if you wish to escape characters you do that by using the \ character.
From the docs on json.org:
A string is a sequence of zero or more Unicode characters, wrapped in double quotes, using backslash escapes. A character is represented as a single character string. A string is very much like a C or Java string.
I have a problem when using GSON library which is json library from Google. Hope someone can give me some hint.
The problem is when I use the gson.fromJson() function trying to convert a json string to a specified defined class.
The example code:
String jsonStr = "{name:"ABC", countries:["US"]}"; // Some Json string.
Gson gson = new Gson();
Example example = gson.fromJSON(jsonStr, Example.class);
class Example {
// does no have no-arg constructor
private String name;
private Integer age;
private JSONArray keywords; // import org.json.JSONArray;
private JSONArray countries;
// other codes
}
The above code is simplied version of my problem.
The problem is in the fromJson() function. The error message is saying "JsonParseException: Expecting object found ["US"]".
I can not figure out what the problem is. I guess maybe gson does not know how to covert a string to JSONArray. Because in here, JSONArray is from another library(org.json).
I try to figure out in the gson documents. It look like I need to write some "Instance Creator" code.
I am wondering whether another can give me some solution. Thank you.
Just make keywords and countries a java List type. I've never seen org.json mixed with gson. Usually gson replaces org.json it's not meant to be used together.
EDIT:
Small example:
class Example {
private String name;
private Integer age;
private List<String> keywords;
private List<String> countries;
public String toString() {
return new Gson().toJson(this);
}
}