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POWhy does this override of a generic method work with 1.6, but not 1.7?
 

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  1. POWhy does this override of a generic method work with 1.6, but not 1.7?
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    <p>Given the following class, which overrides the getListeners method from AbstractListModel:</p> <pre><code>import java.util.EventListener; import javax.swing.AbstractListModel; public class GenericBug extends AbstractListModel { /** * This is the method of interest * This is the exact same method signature that is present in the base class */ @Override public &lt;T extends EventListener&gt; T[] getListeners(Class&lt;T&gt; listenerType) { // do something useful here... return super.getListeners(listenerType); } // Not important here @Override public int getSize() { return 0; } @Override public Object getElementAt(int index) { return null; } } </code></pre> <p>This class compiles fine using an Oracle 1.6 JDK. Trying the exact same class using an Oracle 1.7 JDK, I get compile errors saying there is a name clash, but the method isn't overridden (but it is!!)</p> <p>Here is the error I get when I use JDK7:</p> <pre><code>% /usr/java/jdk1.7.0/bin/javac GenericBug.java GenericBug.java:10: error: name clash: &lt;T#1&gt;getListeners(Class&lt;T#1&gt;) in GenericBug and &lt;T#2&gt;getListeners(Class&lt;T#2&gt;) in AbstractListModel have the same erasure, yet neither overrides the other public &lt;T extends EventListener&gt; T[] getListeners(Class&lt;T&gt; listenerType) { ^ where T#1,T#2 are type-variables: T#1 extends EventListener declared in method &lt;T#1&gt;getListeners(Class&lt;T#1&gt;) T#2 extends EventListener declared in method &lt;T#2&gt;getListeners(Class&lt;T#2&gt;) GenericBug.java:12: error: incompatible types return super.getListeners(listenerType); ^ required: T[] found: EventListener[] where T is a type-variable: T extends EventListener declared in method &lt;T&gt;getListeners(Class&lt;T&gt;) GenericBug.java:9: error: method does not override or implement a method from a supertype @Override ^ Note: GenericBug.java uses unchecked or unsafe operations. Note: Recompile with -Xlint:unchecked for details. 3 errors </code></pre> <p>Can someone explain to me what is happening? Is this a compiler bug in JDK1.7, or am I missing something?</p>
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    1. USwolfcastle
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      1. POWhy does this override of a generic method work with 1.6, but not 1.7?
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      1. POWhy does this override of a generic method work with 1.6, but not 1.7?
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    1. COInclude the declaration of getListeners() from AbstractListModel.
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    2. COThe error message says that the GenericBug.getListeners() method signature does not match the AbstractListModel.getListeners() signature (i.e. does not actually override it), so it is complaining about the @Override annotation.
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    3. CO@DwB `public <T extends EventListener> T[] getListeners(Class<T> listenerType)`
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      1. USCaptain Giraffe
 

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