Attempt to invoke virtual method null point
What is a NullPointerException, and how do I fix it?
Redirect 301 with hash part (anchor) # Are players allowed to pass a penalty kick? Teleporting a player from the overworld to the end Is there any way to teleport a player from the overworld to the end?   Or a way of teleporting a player to a random enderman in the end? Calculating Optimal Geohash Precision from Bounding Box I'm using Elasticsearch's  to plot clusters on a map (using Leaflet). I understand that for larger areas a lower precision setting should be used to limit the number of buckets created/returned.  How should I determine the appropriate precision value to request?  Is there a standard or recommended formula for calculating the optimal precision based on a bounding box and/or zoom level? Is it better to just map zoom levels to precision values (I know that's probably easiest.) Mark a comment as the answer to a question Not to Mention ≈ [Let Alone ≈ Much Less ≈ Still Less] For brevity, I symbolise synonymity with ≈.  So  X ≈ Y  means  X and Y are synonyms.  From : let alone ≈ not to mention  From :  let alone ≈ much less ≈ still less.  Are these all synonyms? What are the similarities and differences between each? I've been trying to prove that given a ring $R$ and a collection of ideals $\{I_{\beta}\}_{\beta \in B}$ in $R$, the set $$\sum_{\beta \in B} I_{\beta}=\{f_1+\cdots+f_r:f_j \in I_{\beta_j}, \mbox{ for some } I_{\beta_j}\}$$ is an ideal and is the smallest ideal containing $\cup_{\beta \in B} I_{\beta}$.  I've already proved when I only have two ideals, and so, using induction, I've seen it for finite sums. But I don't see how to generalise that to an arbitrary family of indexes (maybe infinite) $\beta$.   Could someone please give me a hand? Thank you. $\mathbf L\mathbf D\mathbf L^\top$ Cholesky decomposition is_active_sidebar() Always Returns False Testing random variate generation algorithms Which methods are used for testing random variate generation algorithms? I'm doing a bit of self study, but I'm uncomfortable with a certain idea. I want to show that $f(z)$ is analytic if and only if $\overline{f(\bar{z})}$ is analytic, and by analytic I mean differentiable at each point. Here $f$ is a complex valued function.  What I do is write $f(z)=u(x,y)+iv(x,y)$, where $u$ and $v$ are real functions of two variables. Then $\overline{f(\bar{z})}=u(x,-y)-iv(x,-y)$.  These two forms look very similar, in the sense the one function being differentiable should immediately imply the other is differentiable, since the only thing really changing might be a $-$ sign popping out due to the chain rule.   How can I more rigorously express that $f(z)$ is analytic iff $\overline{f(\bar{z})}$ using this? Many thanks. Make window always on top? I'm a US citizen and I've already gotten my Tier 4 visa to study in the UK in my passport, however, it looks like the start date on the visa and the letter to present to the Immigration Officer has allowed me entry an extra week on top of the usual month. My school starts on September 24th, but my visa states permission to enter on August 17th. I've read that you are only allowed a month before the beginning of school, but my visa is saying differently!  Should I assume its wrong and enter on the 24th or is it okay for me to enter on the 17th?   Thanks. This movie came out around 2000 and was created for one of the cable networks (and never in the theaters).  I think it was on the original Sci-Fi Channel or maybe the USA Network, but really not sure.    It's about a 1950's American-style utopian world.  The main character, if I remember correctly, worked at a car dealership.  I recall him looking like Jon Hamm, Adrian Pasdar, or Scott Bakula, but I may be way off there (and I didn't see the movie in their filmographies).  He drives his nice car home, and the whole town is beautiful, as are its people and white picket fence style homes.     He suddenly starts seeing weird things.  For example, instead of people driving cars, they're actually riding rickety bicycles.  The manicured, paved streets are actually dirt roads.  Houses are, in reality, tiny shacks.  Instead of people's clothes being immaculately maintained, everyone's really wearing filthy rags.  And instead of delicious food, they're eating something that looks like rotten garbage.  Something is making everyone believe they live in a beautiful, perfect society, but it's mind manipulation that's almost on the scale of the movie "The Matrix."    He befriends a pretty lady, and together they travel outside their town and try to find answers.  They even meet an outside militarized government, whose officials are interested in understanding and helping him.  This other city's infrastructure appears to be state-of-the-art and well funded.  The officials all have nice uniforms.  However, their environment is also under the same influence that's making everyone see things differently than what they really are.  The main character somehow sees through this illusion too, and realizes this fake prosperity is affecting others outside his home town--maybe the entire world!    The movie ends with       the man and woman eventually running into some elderly maintenance man in a forested area.  The maintenance man's job is to service a machine that alters everyone's perception of reality.     I posted about this a couple of years ago on another site, and somebody took a guess that it was "The Prisoner" but unfortunately that's not it.  I didn't really explain it well the first time, so hopefully this is clearer. When to use "cannot" versus "can't"? When is it best to write "can't" versus writing "cannot"? Are they interchangeable in every situation? How can I add metadata to NTFS files/folders? I want to tag different file types (i.e. .pdf, .epub, .iso, .bin, folders,..) using the same descriptive fields. For example i would like a metadata field "type" which would be "eBook" on pdf- and epub-files, "CD-Image" on iso- and bin-files.  I read about Alternate Data Streams (ADS) to make this possible. Does anyone know a good program for Windows 7 to tag different files and search for them? It is important for me, that the metadata is NOT stored in a separate database. I move the files a lot and need to stay flexible (ADSs 'stick' to the files).  Any ideas? A geometric sequence has its first term equal to $12$ and its fourth term equal to $-96$.   How do I find the common ratio? And find the sum of the first $14$ terms How to export data with tab delimiters using Apex Data Loader? The internet vaguely says that this is possible. I need this feature to export translation values from a custom object and then import this back into Salesforce using translation workbench. Translation workbench accepts:   Field delimiter: Tab Character delimiter: None   How can we achieve a tab delimited data export from a custom object using Apex Data Loader? popping to root view in navigation controller losing ligatures when switching font series or color in the middle of a word