Gson parsing string without key-value pairs

Question

I am trying to parse a string with the Gson library, but to no avail. Here is my line:

[["-1.816513","52.5487566"],["-1.8164913","52.548824"]] 

The problem in this example is that there are no key-value pairs. I looked at other examples, but they all had key pairs and did not look like my problem.

Answer 1

My solution for parsing a list of strings.

 package stackoverflow.answers; import java.lang.reflect.Type; import java.util.List; import com.google.gson.Gson; import com.google.gson.reflect.TypeToken; public class GsonTest { public static void main(String[] arg) { Gson gson = new Gson(); String jsonOutput = "[[\"-1.816513\",\"52.5487566\"],[\"-1.8164913\",\"52.548824\"]]"; Type listType = new TypeToken<List<List<String>>>() {}.getType(); List<List<String>> strings = (List<List<String>>) gson.fromJson(jsonOutput, listType); for(List<String> inner: strings){ for(String s: inner){ System.out.println(s); } } } } 

But since values ​​can be “conceived” and doubled, you can analyze them directly by changing the type in the solution:

 package stackoverflow.answers; import java.lang.reflect.Type; import java.util.List; import com.google.gson.Gson; import com.google.gson.reflect.TypeToken; public class GsonTest { public static void main(String[] arg) { Gson gson = new Gson(); String jsonOutput = "[[\"-1.816513\",\"52.5487566\"],[\"-1.8164913\",\"52.548824\"]]"; Type listType = new TypeToken<List<List<Double>>>() {}.getType(); List<List<Double>> numbers = (List<List<Double>>) gson.fromJson(jsonOutput, listType); for(List<Double> inner: numbers){ for(Double d: inner){ System.out.println(d); } } } } 

Not important in context, but for future references: Java 7, Gson 2.2.4

Answer 2

One solution with raw types:

 package com.stackoverflow.so18525283; import com.google.gson.Gson; import com.google.gson.GsonBuilder; import java.util.List; public class App { private static final String INPUT = "[[\"-1.816513\",\"52.5487566\"],[\"-1.8164913\",\"52.548824\"]]"; public static void main(final String[] args) { final Gson gson = new GsonBuilder().create(); final List<?> fromJson = gson.fromJson(INPUT, List.class); if (fromJson != null && fromJson.size() > 0 && fromJson.get(0) instanceof List) { System.out.println(((List<?>) fromJson.get(0)).get(0)); // this is a String } } } 

Another solution is to recreate a valid JSON object, the same App as shown below, but with:

 public static void main(String[] args) { final Gson gson = new GsonBuilder().create(); final Foo fromJson = gson.fromJson("{ data: " + INPUT + "}", Foo.class); // TODO: check for null System.out.println(fromJson.data.get(0).get(0)); // this is a Double } private static class Foo { List<List<Double>> data; }