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    <p>I know this is a fairly old question, but I was searching for a solution to generically deserialize nested JSON to a <code>Map&lt;String, Object&gt;</code>, and found nothing.</p> <p>The way my yaml deserializer works, it defaults JSON objects to <code>Map&lt;String, Object&gt;</code> when you don't specify a type, but gson doesn't seem to do this. Luckily you can accomplish it with a custom deserializer.</p> <p>I used the following deserializer to naturally deserialize anything, defaulting <code>JsonObject</code>s to <code>Map&lt;String, Object&gt;</code> and <code>JsonArray</code>s to <code>Object[]</code>s, where all the children are similarly deserialized.</p> <pre><code>private static class NaturalDeserializer implements JsonDeserializer&lt;Object&gt; { public Object deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context) { if(json.isJsonNull()) return null; else if(json.isJsonPrimitive()) return handlePrimitive(json.getAsJsonPrimitive()); else if(json.isJsonArray()) return handleArray(json.getAsJsonArray(), context); else return handleObject(json.getAsJsonObject(), context); } private Object handlePrimitive(JsonPrimitive json) { if(json.isBoolean()) return json.getAsBoolean(); else if(json.isString()) return json.getAsString(); else { BigDecimal bigDec = json.getAsBigDecimal(); // Find out if it is an int type try { bigDec.toBigIntegerExact(); try { return bigDec.intValueExact(); } catch(ArithmeticException e) {} return bigDec.longValue(); } catch(ArithmeticException e) {} // Just return it as a double return bigDec.doubleValue(); } } private Object handleArray(JsonArray json, JsonDeserializationContext context) { Object[] array = new Object[json.size()]; for(int i = 0; i &lt; array.length; i++) array[i] = context.deserialize(json.get(i), Object.class); return array; } private Object handleObject(JsonObject json, JsonDeserializationContext context) { Map&lt;String, Object&gt; map = new HashMap&lt;String, Object&gt;(); for(Map.Entry&lt;String, JsonElement&gt; entry : json.entrySet()) map.put(entry.getKey(), context.deserialize(entry.getValue(), Object.class)); return map; } } </code></pre> <p>The messiness inside the <code>handlePrimitive</code> method is for making sure you only ever get a Double or an Integer or a Long, and probably could be better, or at least simplified if you're okay with getting BigDecimals, which I believe is the default.</p> <p>You can register this adapter like:</p> <pre><code>GsonBuilder gsonBuilder = new GsonBuilder(); gsonBuilder.registerTypeAdapter(Object.class, new NaturalDeserializer()); Gson gson = gsonBuilder.create(); </code></pre> <p>And then call it like:</p> <pre><code>Object natural = gson.fromJson(source, Object.class); </code></pre> <p>I'm not sure why this is not the default behavior in gson, since it is in most other semi-structured serialization libraries...</p>
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    1. POHow can I convert JSON to a HashMap using Gson?
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    1. USKevin Dolan
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    1. COThanks, that was really helpful.
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      1. USMatt Zukowski
    2. CO... although I'm not quite sure what to do now with the Objects I get back. Can't seem to cast them as String even though I know they're strings
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    3. COAha! The trick was the call the deserializer recursively instead of the context.deserialize() call.
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