Exception in thread "main" java.lang.NullPointerException error keeps pointing to the get methods
What is a NullPointerException, and how do I fix it?
Brie Cheese and expiration date I have a Brie Cheese that has not been opened. It shows an expiration date that is 6 weeks ago. Is it still safe to eat? My internal storage capacity is running low,  what can I do? Currently, my internal storage is running low on space.    What can I do besides moving applications to the external memory, as to free up more space, but preserve my current applications and avoid uninstalling?  (Some of them won't be moved) Exclude from * in command line etoolbox and tabularx -- problem with `appto` I'm trying to print worksheets. I have already implemented an automatic numbering for subtasks. I use tabularx for my subtasks (see the MWE below).  Yesterday, I tried to define a new macro called \task that has one optional argument which is the amount of points you can obtain for this particular question. I would like these optional arguments to be gathered with etoolbox's \appto command so that I can print them with my \credits command.  So far, this seems to be ind of struggling as tabularx is working on the tables several times. Every time tabularx calculates the width of X columns the points are appended to \credits which leads to an incorrect list of points.  Is there any way I can solve this problem? I'm currently stucked with this issue.  Plus, I don't know why my \task command does work. Why is the counter subtask not affected by tabularx's several trials?  \documentclass{scrartcl}  \usepackage[utf8]{inputenc} \usepackage[T1]{fontenc}  \usepackage{etoolbox} \usepackage{booktabs} \usepackage{ltablex} \usepackage{xifthen}  \def\credits{} \newcounter{subtask} \setcounter{subtask}{1} \renewcommand{\thesubtask}{\alph{subtask})} \newcommand{\task}[1][]{%     \ifthenelse{\isempty{#1}}{%         \thesubtask%         \stepcounter{subtask}%     }{%         \thesubtask%         \gappto\credits{(#1)}%         \stepcounter{subtask}%     }% }  \begin{document} \begin{tabularx}{\linewidth}[l]{l@{\hspace*{1ex}}X}     \task[1]    &amp;   TEXT1\\     \task       &amp;   TEXT2\\     \task[3]    &amp;   TEXT3 \end{tabularx} \credits \end{document}       The solution given by David Carlisle below causes a table that is too wide. How can this be undone?  \documentclass{scrartcl}  \usepackage[utf8]{inputenc} \usepackage[T1]{fontenc}  \usepackage[a6paper, showframe=true]{geometry}  \usepackage{etoolbox} \usepackage{booktabs} \usepackage{ltablex} \usepackage{xifthen}  \def\credits{} \newcounter{subtask} \setcounter{subtask}{1} \renewcommand{\thesubtask}{\alph{subtask})} \makeatletter \newcommand{\task}[1][]{%     \ifx\hfuzz\@tempdima% %   % tabularx trial do nothing     \else%         \ifthenelse{\isempty{#1}}{%             \thesubtask%             \stepcounter{subtask}%         }{%             \thesubtask%                 \gappto\credits{(#1 BE)\\}%             \stepcounter{subtask}%         }%     \fi } \makeatother   \begin{document}  \begin{tabularx}{\linewidth}[l]{l@{\hspace*{1ex}}X}     \task[1]    &amp;   Some longer text that exceedes the line width.\\     \task[4]    &amp;   TEXT2\\     \task[3]    &amp;   TEXT3 \end{tabularx} \credits  \end{document} Start ubuntu without a desktop environment but start an X application I want to do a small computer just for internet browsing. I dont want to load a desktop environment to keep RAM, CPU and GPU ussage as low as possible. The computer is going to run on a ARM CPU. I dont care with Distro I use, I thought about good old plain Debian. How can I remove the new weather information from the taskbar? Output of getent group What if the Earth stops in its orbit and instead falls straight towards the Sun? The Earth orbits around the Sun because it has angular momentum. If we stopped the Earth in orbit and then let it fall straight towards the Sun, how long would it take to reach the Sun in seconds?  Details and assumptions  The mass of the sun is 2*10^30 Kg. The mass of the earth is 6*10^24 Kg. The earth is 149,600,000 Km from the Sun. You may treat the Earth and Sun as point masses. How does ServerName and ServerAlias work? It's the following part of a virtual host config that I need further clarification on:  &lt;VirtualHost *:80&gt;   # Admin email, Server Name (domain name), and any aliases   ServerAdmin example@example.com   ServerName  141.29.495.999   ServerAlias example.com ...   This is and example config, similar to what I currently have (I don't have a domain name at the moment).  &lt;VirtualHost *:80&gt; - Allow the following settings for all HTTP requests made on port 80 to IPs that this server can be contacted on. For instance, if the server could be accessed on more than one IP, you could restrict this directive to just one instead of both.  ServerName - If the host part of the HTTP request matches this name, then allow the request. Normally this would be a domain name that maps to an IP, but in this case the HTTP request host must match this IP.  ServerAlias - Alternate names accepted by the server.  The confusing part for me is, in the above scenario, if I set ServerAlias mytestname.com and then made an HTTP request to mytestname.com, there would have to be a DNS record pointing to the server's IP for this to work? In which case, is ServerAlias just basically EXTRA ServerName entries?  Say I had a DNS entry such that foobar.com = 141.29.495.999 but then I had ServerName = 141.29.495.999 and ServerAlias was empty, would that mean that although foobar.com gets resolved to the right IP, because there is no reference to accept foobar.com in ServerName or ServerAlias?  Or something. Man I'm confused. I've got a directory shared on my network, using Samba. People on the netwerk use this Samba share to download files from my share to their computers. I'm interested in what files are downloaded most, and by which users they are downloaded. I'd like to see this in real time, if possible. Is there a program that allows me to do this? If yes, how can I use it?    I'm using Ubuntu 11.10. Diagonalisation and characteristic polynomial Let $A\in M_3(\Bbb R)$ which is not a diagonal matrix. Let $P$ be a polynomial (in one variable), with real coefficients and of degree 3 such that $P(A) = 0$. Pick out the true statements:  a. $P = cP_A$ where $c \in\Bbb R$ and $P_A$ is the characteristic polynomial of $A$;  b. if $P$ has a complex root (i.e. a root with non-zero imaginary part), then $P = cP_A$, with $c$ and $P_A$ as above;  c. if $P$ has a complex root, then $A$ is diagonalizable over $\Bbb C$.  I guess b and c are true although I am unable to disprove a. Because A could satisfy $(X-A)$ but this is not a polynomial. Now if $P$ has a complex root, then its conjugate too is its root as the polynomial has  real coefficients. As we all know An odd degree polynomial has always a real root, what we have is three distinct roots. Since $A$ satisfies the polynomial the only difference between the characteristic polynomial and $P$ has to be a constant. When two objects -one of them transparent- intersects it creates some artifacts visible even in the alpha channel. Even with 1024 transparent bounces the artifacts remain.    In the example file there are two cubes in the same position, one transparent and one emission.    What is causing this? Any way to get rid of this artifacts? I read here at  that holding Shift during boot can bring up the GRUB menu. However I try holding one or the other Shift keys, tapping, tapping then holding, nothing works. Am I missing something? How does one access the GRUB menu during boot time?   No dual boot here, just standard Lubuntu 14.04 install. Is it okay to use Stack Overflow as the support forum for a product or project? How can I set CSS only for specific IE browsers? How could the human race be saved in Interstellar? In  (2014) the human race seemed to be facing pretty poor odds until they discovered a convenient wormhole placed by an unknown entity expressed as "they". Later in the movie, we discover that       "they" are actually the human race in the future, reaching back in  time to save itself.   The end of the movie gets a little wild on the physics end, and I'm happy to take that ending as is - no need for it to make sense - but one very basic detail does bother me:  How could the human race have gone back in time to save itself from circumstances that would have caused us to go extinct without our own help (the convenient wormhole)? How to prove that this set is closed? Suppose $Y$ be an ordered set in the order topology. Let $f, g: X \to Y$ be continuous. How to show that the set $\{x| f(x) \leq g(x)\}$ is closed?  This is a excercise from munkres. Maybe trying to show that the set $f(\{x| f(x) &gt; g(x)\})$ is open is suffice. But I could not figure out the connection between this set and the continuity of the two functions.Could you give a hint?  Thanks. Is it possible to install Windows 7 alongside Ubuntu and windows 10 dualboot? I installed windows 10 on my laptop in UEFI mode with HDD GPT disk format, then I installed Ubuntu 16.04LTS on another partition. So I have Ubuntu dualboot with Windows 10 now.  I also installed rEFInd (it's like GUI for you to choose between different OSs) because I don't wanna use Grub2 as the default bootloader. Now I want to have Windows 7 too, but when I boot from the USB stick, an error screen showed up saying something like  the windows boot manager is having problems due to a recent hardware change   My system is still working fine so I don't know if the problem came from my system or if the setup I want is impossible. Height/Radius ratio for maximum volume cylinder of given surface area Remotely changing hard drive boot order, windows 7