Re: Could not get FileSystem obj, get java.lang.NullPointerException !!

[elton sky <el...@gmail.com>]

Thanks for reply,


On Thu, Jun 24, 2010 at 7:35 PM, Steve Loughran <st...@apache.org> wrote:

> elton sky wrote:
>
>> Hi,
>> I am new to hadoop programming.
>>
>
>
> OK. First hint of advice: don't spam the dev lists with user problems, you
> will only get ignored in both mailing lists.
>
>
Get ur advice :)


>
>  I am trying to copy a local file to HDFS. My
>
>  .
>> and when I run it, I got exception:
>> Exception in thread "main" java.lang.NullPointerException
>>
>>        at org.apache.hadoop.conf.Configuration.get(Configuration.java:436)
>>
>>        at
>> org.apache.hadoop.fs.FileSystem.getDefaultUri(FileSystem.java:103)
>>        at org.apache.hadoop.fs.FileSystem.get(FileSystem.java:95)
>>
>>        at HDFSFile.create(HDFSFile.java:42)
>>
>>        at HDFSFile.main(HDFSFile.java:130)
>>
>>        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
>>
>>        at
>>
>> sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
>>        at
>>
>> sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
>>        at
>> java.lang.reflect.Method.invoke(Method.java:616)
>>
>>        at org.apache.hadoop.util.RunJar.main(RunJar.java:156
>>
>> After dug into source code of hdfs, I found the problem happens at
>> "Configuration.getProps()". The value of getProps() is null and,
>> obviously,
>> it shouldn't be.
>>
>
> This is time to reach for your debugger. We don't know why it is null,
> probably something odd with how your configuration is booted up. Follow the
> constructor.
>
> The other tactic, and the one I do first, is search for that stack trace on
> the web and on https://issues.apache.org/jira/ That way, if someone has
> hit the same problem as you, you'll find the solution
>

I mistakenly put :
static {
        URL.setURLStreamHandlerFactory(new FsUrlStreamHandlerFactory());
        }

on the top of the code, which makes the exception. I commented out and it
just works.
I have no idea why this matters?