I am then trying to use the Jackson API to parse the json input stream twice and I get an java.io.EOFException

Question

My ParserCheck.java :-

import java.io.IOException;
import java.io.InputStream;        
import org.apache.commons.io.IOUtils;
import org.codehaus.jackson.JsonParseException;
import org.codehaus.jackson.map.JsonMappingException;
import org.codehaus.jackson.map.ObjectMapper;

public class ParserCheck {

    public static void main(String[] args){
        ObjectMapper objectMapper = new ObjectMapper();

        String responseJson = "{\"status\":\"200\",\"message\":\"Success\"}";
        InputStream streamResponse = IOUtils.toInputStream(responseJson);

        try {
            MyJsonResponse response = objectMapper.readValue(streamResponse, MyJsonResponse.class);
            System.out.println(response);
        } catch ( JsonParseException | JsonMappingException e) {
            e.printStackTrace();
        } catch (IOException e){
            e.printStackTrace();
        }

        try {
            MyJsonResponse response = objectMapper.readValue(streamResponse, MyJsonResponse.class);
            System.out.println(response);
        } catch ( JsonParseException | JsonMappingException e) {
            e.printStackTrace();
        } catch (IOException e){
            e.printStackTrace();
        }finally{
            try {
                streamResponse.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}

My JsonResponse.java:

import org.codehaus.jackson.annotate.JsonIgnoreProperties;
import org.codehaus.jackson.annotate.JsonProperty;

import org.codehaus.jackson.map.annotate.JsonSerialize;

@JsonIgnoreProperties(ignoreUnknown=true)
@JsonSerialize(include=JsonSerialize.Inclusion.NON_NULL)
public class MyJsonResponse {
    @JsonProperty
    private Integer status;

    @JsonProperty
    private String message;

    public Integer getStatus() {
        return status;
    }

    public String getMessage() {
        return message;
    }

    @Override
    public String toString(){
        return "Json Response [Status ="+ status +", Message =" + message + " ]";
    }

}

I get the proper output the first time but the second time I get an exception. This is the output:

Json Response [Status =200, Message =Success ]java.io.EOFException: No content to map to Object due to end of input
    at org.codehaus.jackson.map.ObjectMapper._initForReading(ObjectMapper.java:2775)
    at org.codehaus.jackson.map.ObjectMapper._readMapAndClose(ObjectMapper.java:2718)
    at org.codehaus.jackson.map.ObjectMapper.readValue(ObjectMapper.java:1909)
    at.service.provider.ParserCheck.main(ParserCheck.java:33)

What should be done in this case. I tried closing the stream after the first output but it still gives me the exception.

Answer 1

You're reusing a stream. the first call to

objectMapper.readValue(streamResponse, MyJsonResponse.class);

reads the stream to the end, so when you call it the second time, the stream has no more content. eg.

stremResponse.read() returns -1

Is there any reason you are using a stream? I tried:

            MyJsonResponse response = objectMapper.readValue(responseJson, MyJsonResponse.class);

which works as expected.