@override annotation in JDK 1.6

问题:

I'm using JDK1.6. When I implement an interface and in the implementing class, if I give @override before my function names, Eclipse throws an compilation error. i.e. below code is wrong according to Eclipse.

public class SomeListener implements ServletContextListener {
    @Override
    public void contextDestroyed(ServletContextEvent arg0) {
       // code
    }
    /* other overridden methods here */
}

If I remove @Override annotation, then the code compiles fine. Does it mean that JDK1.6 does not require us to prefix the @override annotation anymore?

回答1:

You probably need to set the compiler compliance level in eclipse. This can be found in Window->Preferences->Java->Compiler

If the compiler preferences are still set to 1.5 the compiler will barf on the override annotation.

Edit: Also check compiler compliance level on a per project basis if you've set those to anything else than default.

回答2:

@Overidde works on method implementation since java 1.6.

---

Resources :

• Sun's forums - Java Programming - Should @Override apply to implementation of interface/abstract methods?
• dertompson.com - @Override specification changes in Java 6
• The Former Weblog of Peter Ahé - @Override snafu

On the same topic :

• When do you use Java's @Override annotation and why?

回答3:

The Java Compiler settings can be at multiple places based on the configuration You choose, One way is to Window->Preferences->Java->Compiler, change that to 1.6 minimum, if it was set to some earlier version. Another way is Right Click on Project-> Properties ->Java Compiler ->JDK Compliance ->Select JDK1.6 minimum, click apply.

After you make the changes, let the project build, it builds and take the changes into affect.

If none of the above options work - Try adding the rt.jar to classpath, it will fix the problem.

回答4:

The @Override annotation changed in Java 1.6 version. In Java 1.5, the compiler didn't allow @Override annotation on implemented interface methods, from 1.6 it does.

You must change java compiler version in properties project -> Java Compiler

回答5:

JDK1.6 definitely supports it. I'm not sure why you would have issues.

What error are you seeing? The only thing I can think of is to make sure that you are using the correct JDK in your project settings. Maybe you are compiling against an older JDK?

回答6:

No the @Override annotation is still used. You should check that the contextDestroyed method is really present in the ServletContextListener interface, and check the imported package for this interface.

回答7:

It sounds like your compiler is set for Java 5, when @Override on interfaces wasn't allowed.