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    <p>You should look at <a href="http://books.google.com/books?id=ka2VUBqHiWkC&amp;pg=PA142&amp;lpg=PA142&amp;dq=effective+java+heterogeneous+type&amp;source=bl&amp;ots=yXLiNgo6T0&amp;sig=t035r7WbwAGmJqGaUOEMRnWGKkU&amp;hl=en&amp;ei=N5QZTffhDoSq8AbogJnKDQ&amp;sa=X&amp;oi=book_result&amp;ct=result&amp;resnum=1&amp;ved=0CBcQ6AEwAA#v=onepage&amp;q&amp;f=false" rel="nofollow noreferrer">Effective Java 2, Item 29: <em>Consider typesafe heterogeneous type containers</em></a></p> <p>The basic idea is that you could imagine you have some <code>Deserializer</code> interface. Then you can have a <code>Map&lt;Class&lt;?&gt;, Deserializer&lt;String, Object&gt;&gt;</code>. The map is basically a registry from type to the proper <code>Deserializer</code> for that type (which deserializes from a String (perhaps you want a json type or something instead of String, but String works) to the type of interest.</p> <p>The real trick is that <em>you must enforce</em> that the class key type matches the deserializer type. i.e. - For some Class that is a key in the map, you have a Deserializer as a value. You can do this with a generic method. For example:</p> <pre><code>&lt;T&gt; void put(Class&lt;T&gt; clazz, Deserializer&lt;String, T&gt; deserializer) { map.put(clazz, deserializer); } </code></pre> <p>Then to use the heterogeneous map, you can use a generic method again:</p> <pre><code>&lt;T&gt; T deserialize(Class&lt;T&gt; typeToDeserializeFromJson, String toDeserialize) { return typeToDeserializeFromJson.cast( deserializers.get(tTDFJ).deserialize(toDeserialize)); } </code></pre> <p>You use the type that is specified by the method caller to</p> <ul> <li>lookup the right `Deserializer` <li>deserialize the json text to an `Object` <li>safely cast the `Object` to the right type which we know is safe because of how we constructed the map in the first place. </ul> <p>I hope what I said was at least somewhat clear. Reading the corresponding entry in EJ2 should help!</p> <p><strong><em>UPDATE:</em></strong></p> <p><a href="https://stackoverflow.com/questions/4544191/how-do-i-correctly-use-generics/4544641#4544641">As Abhinav points out</a>, the GSON library will help you accomplish your final goal of deserializing objects in a way that uses generics appropriately. However, I think your question is more about generics than the end goal so I feel my answer is more appropriate. GSON must be implemented using a heterogeneous type container :-).</p> <p>Thanks, <a href="https://stackoverflow.com/users/526635/abhinav">Abhinav</a> for pointing out GSON!</p>
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    1. POHow do I correctly use generics?
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    1. COPerhaps the example would be more clear if I got rid of the `String` type for `Deserializer`. My intention is that a `Deserializer<F, T>` will deserialize an object of type F to an object of type T.
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    2. COHow would you do this if you had a heterogeneous container? How GSON can know which deserialized to use? Can you set it to look into properties to decide?
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