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1. Liferay hook: filter url giving filterstart error and current url generates exception null    stackoverflow.com

I'm trying to make an autologinfilter in Eclipse using a liferay hook. Now I've added the:

<filter>
    <filter-name>myautologinfilter</filter-name>
    <filter-class>bla.bla.xyz</filter-class>
</filter>
<filter-mapping>
    <filter-name>myautologinfilter</filter-name>
    <url-pattern>/c/login/myurl</url-pattern>
</filter-mapping>

2. Handle a non existing servlet exception    stackoverflow.com

When I type a non-existing servlet in a url an exception error

HTTP Status 404 - 

3. Capture exception generated by     coderanch.com