No content to map due to end-of-input jackson parser

Question

I am getting this response from the server {"status":"true","msg":"success"}

I am trying to parse this json string using Jackson parser library but somehow I am facing mapping-exception stating

com.fasterxml.jackson.databind.JsonMappingException: No content to map due to end-of-input
 at [Source: java.io.StringReader@421ea4c0; line: 1, column: 1]

Why do we get this kind of exceptions?

How to understand what is causing this exception?

I am trying to parse using following way:

StatusResponses loginValidator = null;

ObjectMapper objectMapper = new ObjectMapper();
objectMapper.configure(Feature.AUTO_CLOSE_SOURCE, true);

try {
    String res = result.getResponseAsString();//{"status":"true","msg":"success"}
    loginValidator = objectMapper.readValue(result.getResponseAsString(), StatusResponses.class);
} catch (Exception e) {
    e.printStackTrace();
}

StatusResponse class

@JsonInclude(JsonInclude.Include.NON_NULL)
@JsonPropertyOrder({ "status","msg" })
public class StatusResponses {

    @JsonProperty("status")
    public String getStatus() {
        return status;
    }

    @JsonProperty("status")
    public void setStatus(String status) {
        this.status = status;
    }

    @JsonProperty("msg")
    public String getMessage() {
        return message;
    }

    @JsonProperty("msg")
    public void setMessage(String message) {
        this.message = message;
    }

    @JsonProperty("status")
    private String status;

    @JsonProperty("msg")
    private String message;

    private Map<String, Object> additionalProperties = new HashMap<String, Object>();

    @JsonGetter
    public Map<String, Object> getAdditionalProperties() {
        return additionalProperties;
    }

    @JsonSetter
    public void setAdditionalProperties(Map<String, Object> additionalProperties) {
        this.additionalProperties = additionalProperties;
    }
}

Solution 1

import com.fasterxml.jackson.core.JsonParser.Feature;
import com.fasterxml.jackson.databind.ObjectMapper;

StatusResponses loginValidator = null;

ObjectMapper objectMapper = new ObjectMapper();
objectMapper.configure(Feature.AUTO_CLOSE_SOURCE, true);

try {
    String res = result.getResponseAsString();//{"status":"true","msg":"success"}
    loginValidator = objectMapper.readValue(res, StatusResponses.class);//replaced result.getResponseAsString() with res
} catch (Exception e) {
    e.printStackTrace();
}

Don't know how it worked and why it worked? :( but it worked

Solution 2

In my case the problem was caused by my passing a null InputStream to the ObjectMapper.readValue call:

ObjectMapper objectMapper = ...
InputStream is = null; // The code here was returning null.
Foo foo = objectMapper.readValue(is, Foo.class)

I am guessing that this is the most common reason for this exception.

Solution 3

The problem for me was that I read the response twice as follows:

System.out.println(response.body().string());
getSucherResponse = objectMapper.readValue(response.body().string(), GetSucherResponse.class);

However, the response can only be read once as it is a stream.

Solution 4

I could fix this error. In my case, the problem was at client side. By mistake I did not close the stream that I was writing to server. I closed stream and it worked fine. Even the error sounds like server was not able to identify the end-of-input.

OutputStream out = new BufferedOutputStream(urlConnection.getOutputStream());
out.write(jsonstring.getBytes());
out.close() ; //This is what I did

Solution 5

I had a similar error today and the issue was the content-type header of the post request. Make sure the content type is what you expect. In my case a multipart/form-data content-type header was being sent to the API instead of application/json.

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