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POCasting reference variable in Java
 

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    <p>I have something unclear concerning casting reference variable in Java.</p> <p>I have two classes A and B. A is the super class of B. If I have the two objects, and then the print statement:</p> <pre><code>A a = new A(); //superclass B b = new B(); //subclass System.out.println ((A)b); </code></pre> <p>then what exactly is happening when the println method is executed?</p> <p>I know that because B is a subclass of A, I am allowed to make the following cast:</p> <pre><code>A a2 = (A)b; </code></pre> <p>I also know that when println takes a reference variable as argument, then the toString() method of the class, which has created the object-argument, is invoked (implicitly). This is so, because the method println() is looking for an argument of type String, and the toString() method represent the object as a string. And even if we don't write toString(), the method is invoked - implicitly. So, the following two statements are equivalent:</p> <pre><code>System.out.println (b); System.out.println (b.toString()); </code></pre> <p>So, my question is: what is the implicit action taken when we have </p> <pre><code>System.out.println ((A)b); </code></pre> <p>? </p> <p>I suppose that the type of the reference variable b is automatically changed from B to A. The variable should still be pointing to the same object - the one created with </p> <pre><code>B b = new B(); </code></pre> <p>but just the type of b would be now changed. Is this correct? Another question: even though I have changed the type of b to the type of the superclass, are the overriden methods in the subclass going to be called, and not those of the superclass? </p> <p>Thanks a lot.</p> <p>Regards</p>
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