How to prevent Gson from converting a long number (a json string ) to scientific notation format?

Question

I need to convert json string to java object and display it as a long. The json string is a fixed array of long numbers:

{numbers
[ 268627104, 485677888, 506         


        

Answer 1

Got the same issue, after some investigation here is what I found.

The behavior:

• Gson
  For a number without fractional part, Gson would convert it as Double,
• Jackson
  For a number without fractional part, Jackson would convert it as Integer or Long, depends on how large the number is.

Possible solutions:

• Convert Gson's return value from Double to Long, explicitly.
• Use Jackson instead.
  I prefer this.

---

Code - test for Jackson

ParseNumberTest.java:

import java.util.List;

import org.testng.Assert;
import org.testng.annotations.Test;

import com.fasterxml.jackson.databind.ObjectMapper;

/**
 * test - jackson parse numbers,
 * 
 * @author eric
 * @date Jan 13, 2018 12:28:36 AM
 */
public class ParseNumberTest {
    @Test
    public void test() throws Exception {
    String jsonFn = "numbers.json";

    ObjectMapper mapper = new ObjectMapper();

    DummyData dd = mapper.readValue(this.getClass().getResourceAsStream(jsonFn), DummyData.class);
    for (Object data : dd.dataList) {
        System.out.printf("data type: %s, value: %s\n", data.getClass().getName(), data.toString());
        Assert.assertTrue(data.getClass() == Double.class || data.getClass() == Long.class || data.getClass() == Integer.class);

        System.out.printf("%s\n\n", "------------");
    }
    }

    static class DummyData {
    List