How does inheritance of instance fields work in this particular code?
Is there a way to override class variables in Java?
Is adjoint of singular matrix singular? What would be its rank? Prove $-(-a)=a$ using only ordered field axioms I need to prove for all real numbers $a$, $-(-a) = a$ using only the following properties:     I tried by starting with P12 written using symbolic logic:  $\begin{align} \forall a,b \in P \to &amp; a \cdot b \in P \Leftrightarrow True \\ \forall a \in P \land \forall b \in P \to &amp; a \cdot b \in P \Leftrightarrow True \\ \lnot \left[ \left( \forall a \in P \right) \land \left( \forall b \in P \right) \right] \lor &amp; a \cdot b \in P \Leftrightarrow True \\ \exists a \notin P \lor \exists b \notin P \lor &amp; a \cdot b \in P \Leftrightarrow True \\ \end{align} \\ $  and played with evaluating it with $b = -1$, $-a$ and so on. But, felt this wasn't really a solution because the last symbolic logic statement above is ambiguous.  Not to mention--other than P12--I haven't used any of the axioms listed above whatsoever. ( And I've not bothered to prove any of the theorems of symbolic logic I have used. )  Can anyone give me a start on this problem?  Many thanks in advance.  Edit  Thank you, everyone! .  Best regards! Better explanation of the common general relativity illustration (stretched sheet of fabric) I've googled and also searched the answers here but couldn't find my problem so here goes:  I know how to bevel a curve using another object and when I try it with a normal circle it's fine. But I'm trying to use this flat oval shape to bevel a larger curve of the same shape and it's not following the curve at the correct rotation. I've tried everything, rotating the bevel object, clicking random options in the object data menu.. I can't seem to budge it from looking how it is in the screenshot. In the screenshot you can see the curve I've failed to bevel correctly and also the bevel object in the bottom right.  Basically, I want the flat part of the oval to be above and below the curve, not on the sides as it is. I hope that makes sense. Anyone know what I need to do? What I am trying to do is to set a date in my date field and also update the object. I am using the class below to do so which works just fine in my sanbox but in production I am getting this error:      System.LimitException: Too many query rows: 50001   public with sharing class updateObject{     public  List&lt;NRProducts__c&gt;  values;     public PageReference updateObject() {         values=[SELECT Refreshed_Date__c FROM NRProducts__c ];         for (NRProducts__c s :values){            s.Refreshed_Date__c =Date.today();          }          update values;         return null;                       }     }   VF Page:  &lt;apex:page showheader="false" controller="updateObject" sidebar="false"&gt; &lt;apex:form&gt;  &lt;apex:commandButton action="{!updateObject}" value="Update"/&gt; &lt;/apex:form&gt; &lt;/apex:page&gt; Can a shell script set environment variables of the calling shell? I'm trying to write a shell script that, when run, will set some environment variables that will stay set in the caller's shell.  setenv FOO foo   in csh/tcsh, or  export FOO=foo   in sh/bash only set it during the script's execution.  I already know that   source myscript   will run the commands of the script rather than launching a new shell, and that can result in setting the "caller's" environment.  But here's the rub:  I want this script to be callable from either bash or csh.  In other words, I want users of either shell to be able to run my script and have their shell's environment changed.  So 'source' won't work for me, since a user running csh can't source a bash script, and a user running bash can't source a csh script.  Is there any reasonable solution that doesn't involve having to write and maintain TWO versions on the script? What is a Superblock, Inode, Dentry and a File? From the article  by M. Tim Jones, I read that Linux views all the file systems from the perspective of a common set of objects and these objects are superblock, inode, dentry and file. Even though the rest of the paragraph explains the above, I was not that comfortable with that explanation. Could somebody explain to me these terms? Formula between wire size and current Is there a mathematical formula between wire size, current, temperature and wire type(Or resistance)? Correct way of mounting a Windows share I mounted a Windows share to my Ubuntu 11.10 system via adding the following line to the /etc/fstab:  //serveraddr/sharedfolder /mnt/foldername/ smbfs credentials=/home/myname/.smbpasswd 0 0  using the .  But there's a problem with the permissions. The owner of the mount folder is root. I can not create any folders or files in the mounted point is I don't become the root. Even I can not change the ownership to my default user via   sudo chown -R myname .  I googled and saw that it might stem from the fact that Windows file formats (fat32/ntfs) can not save ownership. But when I connect to the same location via samba as   smb://serveraddr/sharedfolder  by providing my credentials, I have the privileges to write without being the root.  How can I make it to let me write to the mounted folder? ST_Length (GEOM, true) for calculating distances in Geographic Reference System How to plot a graph from its adjacency matrix and coordinates of vertices? A similar question is . If we give all the data of the vertices's coordinates and the graph's adjacency matrix, how to plot it with tikz, pstrick or other tool in tex?   here are the data of adjacency matrix and coordinates  Coordinates:{{0.809,0.588},{0.309,0.951},{-0.309,0.951},{-0.809,0.588},{-1.,0.},{-0.809,-0.588},{-0.309,-0.951},{0.309,-0.951},{0.809,-0.588},{1.,0.}}  Adjacency matrix: {{0,1,0,0,1,0,1,0,0,1},{1,0,1,0,0,1,0,1,0,0},{0,1,0,1,0,0,1,0,1,0},{0,0,1,0,1,0,0,1,0,1},{1,0,0,1,0,1,0,0,1,0},{0,1,0,0,1,0,1,0,0,1},{1,0,1,0,0,1,0,1,0,0},{0,1,0,1,0,0,1,0,1,0},{0,0,1,0,1,0,0,1,0,1},{1,0,0,1,0,1,0,0,1,0}}   Sometimes the number of data is too large to put the data in the main tex file. It would be better to import the data from external files. . Is it possible to exclude questions I've already answered from the search criteria? Recently I asked if it were possible to find questions with just one answer and as a result we got an .  That's great, but ...     Is there a way to restrict the search to questions where that one answer isn't mine? That would help. :-)   It's certainly possible to search for , but it's not possible to exclude your own posts as far as I can tell:   -user:me searches for posts that . user:1-67 doesn't search for posts from user #1 to user #67, but searches for .  (And I'm not sure that will help anyway since I don't think it would be possible to simultaneously exclude 69-max(userID).) -Ericson searches for posts that , but since my last name is in the the metadata and not the searchable portion of posts: no joy.   And of course none of this will actually work to eliminate the questions that that I've answered already and want to ignore.  In general, If I'm involved in a Q&amp;A (or ) the notification procedures do a good job of keeping me up-to-date with developments.  But when I search, it's often to find questions I've not noticed before.  So being able to eliminate questions I have already answered would be a generally useful feature for me. How to sort a list of objects based on an attribute of the objects? This is what is supposedly his claim:     My noumenal self is an uncaused cause outside of time, which therefore   is not subject to the deterministic laws of nature in accordance with   which our understanding constructs experience.   How can he say that if a noumenal self has to exist in nature and be bound to body that exists in nature? Also, if his noumenal self is free then so does 7 billion other people's, which is not the case because they all live in a societal structure where everyone has freedom that comes with a bunch conditions as to what is forbidden. One-sided Fisher's exact test and its complement Migrating to full Ubuntu after dual installation on WinXP I previously ran 12.04 alongside WinXP to see how it performed on my mom's older laptop.  i also migrated her email to Thunderbird. If I now convert from dual WinXP/Ubuntu to only run Ubuntu will things like her Thunderbird emails be transferred as part of the Ubuntu full install? Or must I do something else? I am fairly tech aware, but not a full IT boffin! How to pad zeroes to a string? Possible Duplicate:             TL;DR: sudo apt-get install ... saying "Unable to correct problems, you have held broken packages."   The problem  I was trying to get the WebApps feature for PP and QQ following .  I ran the sudo add-apt-repository ppa:webapps/preview command to add the repository, but i got a connection error. Since I know my current ISP gives a shaky connection, I tried again and sure enough, it worked.  Then I ran sudo apt-get install unity-webapps-preview, but I realized we had to update apt-get first, so I hit Ctrl + C to stop it. Then I ran sudo apt-get update which worked w/o a fuss, but when I ran sudo apt-get install unity-webapps-preview again later, it showed an error message. Here's the dump:  Reading package lists... Done Building dependency tree        Reading state information... Done Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming. The following information may help to resolve the situation:  The following packages have unmet dependencies:  unity-webapps-preview : Depends: xul-ext-unity but it is not going to be installed                          Depends: xul-ext-websites-integration but it is not going to be installed                          Depends: xul-ext-webaccounts but it is not going to be installed E: Unable to correct problems, you have held broken packages.   I think this might be because of me interrupting the earlier command. It hadn't got a chance to output anything, though — I stopped it pretty fast.  What I tried  Commands  I tried these:-   sudo apt-get install --fix-broken sudo apt-get autoclean sudo apt-get autoremove sudo apt-get -f install   But even after running sudo apt-get upgrade after every try, none of them worked.  Purging  I tried purging the repository, but that didn't work either. First, I got the package using sudoapt-get install ppa-purgeand then tried to purge the WebApps repo usingsudo ppa-purge ppa:webapps/preview`.  Manually installing dependencies  If you look at the error dump carefully, it says:     Depends: xul-ext-unity but it is not going to be installed   Depends: xul-ext-websites-integration but it is not going to be installed   Depends: xul-ext-webaccounts but it is not going to be installed   So I tried installing them manually. I ran sudo apt-get install xul-ext-unity, but got this:     Depends: xul-ext-websites-integration but it is not going to be installed   Breaks: firefox (>= 15.+) but 16.0~b6+build1-0ubuntu0.12.04.1~mfn4 is to be installed   I have no idea what the second part means, but I tried resolving the first. Running sudo apt-get install xul-ext-websites-integration gave:     xul-ext-websites-integration : Breaks: firefox (>= 15.+) but 16.0~b6+build1-0ubuntu0.12.04.1~mfn4 is to be installed   As a last resort, I tried sudo apt-get install xul-ext-webaccounts, but that gave the sane message too:     Breaks: firefox (>= 14.+) but 16.0~b6+build1-0ubuntu0.12.04.1~mfn4 is to be installed   What does Breaks: firefox (&gt;= 14.+) but 16.0~b6+build1-0ubuntu0.12.04.1~mfn4 is to be installed mean?  Research  I tried searching , looking at a couple of , looking at  and searching on AU, but to no avail. Help would be appreciated. To put it simple, there's a simple java swing app that consists of JFrame with some components in it. One of the components is a JPanel that is meant to be replaced by another JPanel on user action.  So, what's the correct way of doing such a thing? I've tried  panel = new CustomJPanelWithComponentsOnIt(); parentFrameJPanelBelongsTo.pack();   but this won't work. What would you suggest? What is the easiest way to resolve apt-get BADSIG GPG errors?