How to get rid of null value exception I want to sum up all values in the cells of the rows and write the aggregated value in the bottom of the  table.  I use this code  double Sum[] = new double[sheet.getRow(0).getLastCellNum()]; for (int i = 1; i &lt; LastCellNum; i++) {     Sum[i - 1] = 0;      for (int j = 1; j &lt;= LastRowNum; j++)     {         cell = sheet.getRow(j).getCell(i);         if (cell != null)         {             try             {                 Sum[i - 1] = Sum[i - 1] + cell.getNumericCellValue();             }             catch (NumberFormatException | NullPointerException ex)             {                 //Handle NumberFormat and NullPointer exceptions here             }             catch (Exception ex)             {                 //Handle generic exception here}             }         }     }     System.out.println(Sum[i - 1]);   The code works properly and it could even print the Value of Sum, but after that I have java.lang.NullPointerException. All the selected Cells in my file are either empty or contain numbers.
What is a NullPointerException, and how do I fix it? What are Null Pointer Exceptions (java.lang.NullPointerException) and what causes them?  What methods/tools can be used to determine the cause so that you stop the exception from causing the program to terminate prematurely?
While studying I read about the principle of underdetermination of scientific theories. I made some researches online but I am more confused than before. I read about the Quine-Duhem holistic thesis, but I do not know if is the same as underdetermination. Triggered by a  I was wondering what actually would happen to a ship (e.g. the Enterprise-D NCC-1701) that collides with a stationary object such as a) another ship of a similar configuration or b) a gigantic structure like a moon or even a planet.  We know the deflector is supposed to keep interstellar dust (not to be confused with ordinary dust, which is a different thing) from ripping large holes in the ship.  At first, one thinks "Obvious. ." But does it really? Would the deflector manage to actually deflect both masses? If not, where is the threshold of what a deflector can handle? Would the ship maybe tunnel right through the object, because of wibbly-wobbly space wobblification by the warp field? It does do some weird things to the space right in front and behind the vessel.  Important remark: We cannot approach this with what we know about physics at all. For all intents and purposes, both ships must measure the other ship travelling faster than light, resulting in it having infinite (or rather undefined) mass and by extension momentum. If we start with that reasoning any ship jumping to warp would suck in the entire universe (it takes a moment, but think about it). So, obviously we cannot apply our intuition (even our relativistic intuition) here. (mód 1) is not copied correctly Please consider the following MWE:  \documentclass{article} \usepackage[spanish]{babel} \selectlanguage{spanish} \usepackage[utf8]{inputenc} \usepackage[T1]{fontenc}  \begin{document} Works: áéà  Does not work: \(\pmod1\) \end{document}   The áéà text is copied correctly, but if I try to copy (mód 1) it says: (m´od 1).  Does anyone know why this happens? How is it solved?  Thanks! How to compute moments of log normal distribution? The computed moments of log normal distribution can be found . How to compute them? Why is this simple Excel calculation not netting Zero? If a function returns no value, with a valid return type, is it okay to for the compiler to return garbage? How can I reliably get the operating system's name? I am really confused.  Which preposition is correct?     She is in/at the park.   They are in/at the park.   I am in/at the park.   Should I use in or at in these sentences? Obtaining remote host name in bash script Sorry my knowledge of Linux bash commands is pretty basic, I've been searching for a while but I'm not 100% sure what I need to search for.  I was wondering if there's a way to grab the current logged in users remote host name in a Linux bash script? I have a script in which I need to log each time a user runs it. I'm obtaining the date like so:  cdat=`/bin/date +%a' '%d' '%h' '%Y', '%H':'%M`;   I now need to add the users remote host (not the username they logged in with). I'm not 100% sure I'm using the right terminology here either, just to clarify; by 'remote host name' I mean the same output that prints on the screen on most servers I've logged into over ssh, for example:  Last login: Mon Jul 22 16:35:09 2013 from win7-i7-stuart.my.domain.com   I'm looking for the win7-i7-stuart.my.domain.com bit. Windows 10 default programs keep changing Since the fall update last month, Windows 10 automatically keeps changing the default apps for certain types (mostly browser,pdf,mp3,jpg). I have tried changing them back from the Settings app as well as the Control Panel.  I have observed that this happens mostly while unzipping files using WinZip. Windows changes the default programs back to Microsoft recommended programs such as Edge, Photos, Groove etc.  Is there a way to restrict this from happening? Has anybody else encountered a similar situation? I couldn't find similar question anywhere so I'm asking this here. How to update Android Studio in Ubuntu? I am trying to update from version 2.0.0 to version 2.1.2 in Ubuntu 64bit/14.04LTS but when I click "update and restart" it says "Downloading patches" and it closes.   It does not start again and if I try to open it, the version is still 2.0.0.   Is there any tutorial to manually update android studio? (keep all settings and etc). How do you add more than one material to a mesh?   I have tried adding two materials to the object, and then assigning one of the materials to a vertex-group, but I could not find a place to assign it.  I am making a striped bouncy ball that I want to deform, so adding a different material by separating the mesh into different objects would not be ideal. System App Permissions I have an application that needs root permissions to run.  No biggie, all of my personal devices are rooted, so I am very comfortable with the process. The problem is that this application is to be used on company owned devices issued to certain employees and I don't want them to be able to uninstall the application nor do I want them having root access to the device.  I was thinking that the following process would accomplish my goals:   Root the device Install my app as a system app Launch the application and grant su rights to it Unroot the device   Since it would be a system app, and the device wouldn't be rooted, users would be prevented from removing the app.  What I am unsure of is whether or not that application would retain its root privileges once the device is unrooted?   Any feedback or insight would be greatly appreciated! How do you combine two jQuery search results? eg:  var $allFoos = $('.foo'),     $allBars = $('.bar')     $allFoosAndBars = $allFoos + $allBars;   Obviously, I just made up that last line, but I hope it makes it sorta clear what I mean. To be clear, the example is greatly simplified, and it could be any arbitrary sets i'm talking about, so $('.foo, .bar') is not what I'm after. Firstly my main goal is to try and get FTP files recursively in Centos.  However the actual FTP login contains an @ which ruins the syntax.  Is there some way to place the username in "double quotes" or some such equivalent such that I can use @in the username? Is there a way to disable file:/// protocol in google chrome?  Is there some option, or some switches that can disable this feature?  Please help So I had  closed within eight minutes of asking.  Is this a little fast? Not only do I object to the reason it was closed (not a real question, come on I'm asking for decent books!), but it was closed insanely fast. Should there be a grace period for questions (diamond mods exempt if so) before they can be voted on to be closed? insert code keywords inline What is the command to insert inline code words into the text like this?   I know there are packages for inserting snippets into the code, but I need to insert keywords within the main text. I was wondering if there is a more convenient way to do that. How to convert Wubi install into regular install? I have some simple python code that searches files for a string e.g. path=c:\path, where the c:\path part may vary. The current code is:  def find_path(i_file):     lines = open(i_file).readlines()     for line in lines:         if line.startswith("Path="):             return # what to do here in order to get line content after "Path=" ?   What is a simple way to get the text after Path=?