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POgenerics and inheritance question
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copied!<p>I have three classes:</p> <pre><code>public abstract class fileHandler<Key extends Object, Value extends Object> { } public A extends fileHandler<String, String[]> { } public B extends fileHandler<String, String> { } </code></pre> <p>Now in my main function i do something like this:</p> <pre><code>fileHandler file= null; If (<condition>) { fileHandler = new A(); } else fileHandler = new B(): } </code></pre> <p>But this gives 2 compile time errors:</p> <ol> <li>Cannot convert A to fileHandler</li> <li>Cannot convert B to fileHandler</li> </ol> <p>How can I get rid of these errors as I don't get this error if base class is not generic.</p> <h3>Update:</h3> <p>My class hierarchy is:</p> <ol> <li><code>class fileHandler<Key, Value> { }</code> </li> <li><code>class A extends fileHandler<String, String[]> { }</code> </li> <li><code>class B extends fileHandler<String, String> { }</code> </li> <li>class C that calls function <code>gen(object of A)</code> or</li> <li>class D that calls function <code>gen(object of B)</code>. </li> <li>both C and D are derived from abstract class E.</li> </ol> <p>Now how should I define these functions in C and D and E:</p> <p>I gave the following:</p> <h3>E:</h3> <pre><code>public abstract void gen (fileHandler A) throws exception; </code></pre> <h3>C:</h3> <pre><code>void gen (fileHandler A) throws exception; </code></pre> <h3>D:</h3> <pre><code>void gen (fileHandler A) throws exception; </code></pre> <p>C, D, and E give error fileHandler is raw type. Reference to generic type fileHandler(Key, Value) should be parameterized.</p>

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