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POjava force a methods parameter object type based on instance variable
 

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    <p>Can i force a compile error based on a method instance variable? Consider the example classes below. </p> <pre><code>class MyObject{ Class targetClass; public MyObject(Class&lt;? extends Model&gt; targetClass){ this.targetClass = targetClass; } public &lt;T extends Model&gt; void doSomething(T model){ //do some stuff } } class Customer extends Model {} class Document extends Model {} </code></pre> <p>Could i instantiate <code>MyObject</code> with the <code>Customer.class</code> and then have it throw a compile error if i then call the <code>doSomething()</code> method with a <code>Document.class</code> instance? </p> <pre><code>MyObject object = new MyObject(Customer.class); //this shouldn't compile object.doSomething(new Document()); //this would be able to compile object.doSomething(new Customer()); </code></pre> <p>Edit*</p> <p>I'm trying to come up with an ORM Relationship object. I'm instantiating the object with a base <code>Model</code> instance and a target class. For example, i'm creating a <code>HasMany</code> relationship object. I would instantiate the object with a <code>Customer</code> instance and a <code>Document</code> class. In my <code>HashMany</code> object i have a <code>.get()</code> method which returns all <code>Documents</code> attached to the <code>Customer</code> instance. I also have an <code>.attach(Model model)</code> method where i would feed it a <code>Document</code> instance and the method would attach the <code>Document</code> model to the <code>Customer</code> model in the database. I would like to force the <code>.attach(Model model)</code> method to only accept models from the class that the object was instantiated with. In this case, the <code>Document</code> class.</p>
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    1. USDavid
    1. USDavid
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    1. COThis smells like a case of [the XY problem](http://meta.stackexchange.com/questions/66377/what-is-the-xy-problem). What are you actually trying to accomplish?
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      1. USMatt Ball
    2. CO@MattBall, I edited my OP with more info
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      1. USDavid
    3. COWhy not generics? `MyObject<Customer>`?
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