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    <p>Generics work at compile-time. The reason super-type tokens work, is because (anonymous) inner classes can access the type arguments to their generic superclasses (superinterfaces), which in turn are stored directly in the bytecode metadata.</p> <p>Once your .java source file is compiled, the type parameter <code>&lt;T&gt;</code> is obviously thrown away. Since it is not known at compile time, it cannot be stored in bytecode, so it's erased and Gson can't read it.</p> <p><strong>UPDATE</strong></p> <p>After newacct's answer, I tried to implement what he suggested in his option 2, ie implementing a <code>ParameterizedType</code>. The code looks like this (here is a basic <a href="http://pastebin.com/PV6cP9jc" rel="noreferrer">test</a>):</p> <pre><code>class ListOfSomething&lt;X&gt; implements ParameterizedType { private Class&lt;?&gt; wrapped; public ListOfSomething(Class&lt;X&gt; wrapped) { this.wrapped = wrapped; } public Type[] getActualTypeArguments() { return new Type[] {wrapped}; } public Type getRawType() { return List.class; } public Type getOwnerType() { return null; } } </code></pre> <p>the purpose of this code, is to be used inside <code>getFromJsonList()</code>:</p> <pre><code>public List&lt;T&gt; fromJsonList(String json, Class&lt;T&gt; klass) { Gson gson = new Gson(); return gson.fromJson(json, new ListOfSomething&lt;T&gt;(klass)); } </code></pre> <p>Even if the technique works and is indeed very clever (I didn't know it and I would have never thinked of it), this is the final accomplishment:</p> <pre><code>List&lt;Integer&gt; list = new Factory&lt;Integer&gt;() .getFromJsonList(text, Integer.class) </code></pre> <p>instead of</p> <pre><code>List&lt;Integer&gt; list = new Gson().fromJson(text, new TypeToken&lt;List&lt;Integer&gt;&gt;(){}.getType()); </code></pre> <p>To me, all this wrapping in useless, even if I agree that <code>TypeToken</code>s make the code look nasty :P</p>
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    1. POJava Type Generic as Argument for GSON
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    1. COpretty clear, sadly looks limited
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      1. USRodrigo Asensio
    2. COIt is. The key point to understand is that in order for the *super-type token machinary* to work, we must create a ficticious anonymous class, ie a piece of bytecode that has even its own `Outer.$N.class` file. This is the trick that makes `TypeToken` work, but can't really work in your case, because when the supplied method source is compiled, the `Class<T>` argument fo `fromJSonList` is erased
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    3. COIt's not "erased" in the `Type`. Rather, the generic argument will be stored as a `TypeVariable` rather than a `Class`
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