What is the difference between != and =! in Java?
What's this =! operator?
System.FinalException: Record is read-only: Trigger.updateCompetitors: line 24 I am writing a trigger to get all the Opportunity competitors into a field on Opportunity, however, getting an error while testing it.  Error: updateCompetitors: execution of AfterUpdate caused by: System.FinalException: Record is read-only: Trigger.updateCompetitors: line 24  Can you please check the below code and suggest me what's wrong with this?  trigger updateCompetitors on Opportunity(after insert, after update){    List&lt;Opportunity&gt; OppIds = new List&lt;Opportunity&gt;();     for (Opportunity opp: trigger.new){         OppIds.add(opp);     }  List&lt;OpportunityCompetitor&gt; oppComps = new List&lt;OpportunityCompetitor&gt;();  oppComps= [select id, CompetitorName, Strengths, Weaknesses from OpportunityCompetitor where OpportunityId in: Trigger.newMap.keySet()];  List&lt;Opportunity&gt; OppstoUpdate = new List&lt;Opportunity&gt;();   for (Opportunity opp: OppIds){     String allcomps = null;      if( oppComps.size()&gt;0 ) {       for (integer i = 0; i &lt; oppComps.size(); i++){          allcomps = allcomps + oppComps[i].CompetitorName+',';       }     }    opp.OpportunityCompetitors__c = allcomps;    OppstoUpdate.add(opp);  }    update OppstoUpdate; } I have both Windows 7 and Ubuntu installed on a shared machine. Because a lot of the non-developers use Windows, I'd like to change the boot order to make it easier for them.  Currently the boot order looks like the following:   Ubuntu 11.10 kernelgeneric *86 Ubuntu 11.10 kernelgeneric *86 (safe boot)  Memory test Memory test Windows 7 on /dev/sda6   How do I change the default order so that Windows 7 is at the top of the list?   Windows 7 on /dev/sda6 Ubuntu 11.10 kernelgeneric *86 Ubuntu 11.10 kernelgeneric *86 (safe boot)  Memory test Memory test The Software Center in Ubuntu 16.04 (Gnome Software) shows only part of the packages available. While e.g. apt list qtcreator correctly lists the corresponding package a search in Software Center finds nothing.  Is there something misconfigured? I upgraded from 15.10. Until now I have used the old Ubuntu Software Center which worked fine. In particular, when $x=y=z$ isn't the above expression equal to 1 and not -1? Uploading an image from the web can leave paste broken in editor Chat messages should use consistent icon in iOS app It'd be nice if the chat notifications in the feed used the default Stack Exchange icon like the ones in the inbox do*:     Since items in the feed are grouped so that multiple items from the same site , the site icon helps delimit grouped items a bit less subtlely than the grey divider lines, and chat replies' lack of one causes them to sort of blend in to the previous group.  *Ideally it'd use the icon of the site the room was associated with, but I don't think that information is readily available What is the view on accounts shared by multiple users on Stack Overflow? It has been my understanding that accounts are suppose to be for a specific user. This user, , is a company: . No doubt, this account has provided some quality answers. However, if a specific user cannot be identified, I don't think that the rep gain, rewards, or badges should be given. This should somehow be tagged as a 'Corporate User'. The rep has no real value when you can't be somewhat sure that the same person is giving the answers all the time.  This is where I found an answer by Devart: , peddling a product.    Edit 2 Good points have been brought up and most I can agree with. But we are setting a precedent. Meta Fudgey brought up a good point about the account's ability to use mod tools responsibly and consistently. Maybe this feature is not available to an account that appears to be an umbrella account unless a single user is identified. I think it is important to consider this aspect.    Let me re-iterate: the user(s) has provided excellent content and I would want that to continue. However, there is more at stake here than meaningful content and helpful resources.      Edit The view on 'shared' accounts wasn't so bright a year ago. For most of us, we have information in our profiles that identifies us as individuals. No, I don't have absolute knowledge of the activities on this account and how many people might use it. Meh, for all we know it could be a knowledgeable programmer with some good PR sense. On the other hand, it could be a PR person with no programming knowledge getting the answers from an employee. Who knows... How to read dash files Image of the tensor product of strict maps of Banach spaces modify specific column with sed or awk I have a CSV file that looks like this:  qw12er,foo,0 bn5mgh rt8yp,foo,10 gh78jk bn852mv,foo,852 78ghjkh tgbr,foo,10 ujmyhn wsx2d,foo,0000 ui52ohn tgbr,foo,7418529 ujmyhn ikl896o,foo,22 wsxdc52   I want to modify the 3rd column and remove all numbers and space from the beginning of the 3rd column.  Then output would be as follows:  qw12er,foo,bn5mgh rt8yp,foo,gh78jk bn852mv,foo,78ghjkh tgbr,foo,ujmyhn wsx2d,foo,ui52ohn tgbr,foo,ujmyhn ikl896o,foo,wsxdc52 I recently upgraded Windows 7 to Windows 10. The biggest issue I have now is that the Windows Search service no longer works, making the Start menu mostly unusable.  If I go to Indexing Options in the control panel I see that Indexing is not running and the list of paths to index is empty.  Going to advanced options, the current index path is empty, and the new path is empty too. This is true even if I try to use the "New Index" button.  Using the troubleshooter won't help since the service doesn't start. If I try to manually start the "Windows Search" service, I get the error  "Error 3: Unable to find specified path" (this is the rough translation, the original message is in my language).  What can I do to find out which path/file is missing ? I tried to check with Process Monitor, but the only file (beside system libraries) the SearchIndexer.exe try to access seem to be c:\ProgramData\Microsoft\Search\Data\Application (everytime the service is started the whole folder c:\ProgramData\Microsoft\Search is deleted and recreated) and C:\Windows\System32\config\systemprofile (which exists).  Edit: all available updates are installed, and issuing      SFC /scannow   Doesn't reveal any issue Objects disappear when looking through camera When I go to camera perspective, there are parts of my object that I can't see. I tried adding and deleting my camera a lot of times and positioning it so that the objects I would like to see on my camera view will be seen but to no avail, I still get the same problem.    What could be wrong with my camera set-up? Pacf lag axe , is not an integer I'm trying to use ARIMA process to predict the behaviour of a time series, the probleme I face is that I can't get the order of each component of ARIMA, the lag is between 0 and 1, same goes for the acf. The time series has no tendency, and I guess no seasonality.     My question is : Does this mean that ARIMA orders are all 0s, and if so, is the HoltWinters a good (or the best) solution for modelling this kind of TS ? Find the determinant of $I + A$ What wand was used by Mr Graves at the time of Fantastic Beasts? We know that the movie Fantastic Beasts is set in 1926. From the movie, we learn that at this time, Dumbledore is a teacher at Hogwarts and Grindelwald is lose after escaping a previous arrest. In the movie we learn that      Mr Graves is in fact Grindelwald in disguise. Grindelwald is shown to be at least in his forties, maybe fifties so he should already be the owner of the wand since he stole it from Gregorovitch as a teen.   We know that Dumbledore won the wand from Grindelwald after defeating him in their historic duel. That duel is always described as being “the end of the dark wizard Grindelwald” so I’m assuming that it didn’t happen prior to the movie and that he didn’t escape after that duel, please correct me if you have cannon evidence stating the contrary.      In the movie, we see Graves’ wand a few time and it isn’t the (very recognizable) one used in DH as the Elder Wand. This could of course be a prop error but since David Yates was also the director on DH and a lot of the visuals are similar I’m assuming it wasn’t. Graves could of course be using another wand in the fear that someone could recognize it but he would still be the rightful master of the Elder Wand. At the end of the movie, Newt is the one that disarms Graves/Grindelwald.   In all logic, he should have been made the new owner of the wand, whether Grindelwald was actually using it or not. That would have made it impossible for Dumbledore to win it from Grindelwald later.  So my question is: What wand is that character using at that specific time? Is he already the owner of the Elder Wand?      And if so, why wasn’t Newt made the new owner of the wand? Environment for two columns with lstlistings In order to reduce copy-pasting, I want to create an environment that will produce a two-column table with headers and two listings in different languages, like below:  \begin{tabular}{l l} Python &amp; Haskell \\ \hline \\ \lstset{language=Python} \begin{lstlisting} A \end{lstlisting} &amp; \lstset{language=Haskell} \begin{lstlisting} B \end{lstlisting} \end{tabular}   I want to use it like below, hiding everything but code:  \begin{comparison} A \vs B \end{comparison}   So far I tried making two new environments (instead of a \vs command inside) with \lstnewenvironment, where first environment had \tabularx command and second \endtabularx. I also tried creating normal \newenvironment for this tabular, &amp; for \vs command and manually inserting \begin{lstlistings} and \end{lstlistings} with code, but it stopped compiling when I put lstlistings inside.  How can I create such an environment?  EDIT: The most compact version I've came up with until now is  \newenvironment{comparison} {\begin{parcolumns}[nofirstindent,distance=0pt,colwidths={1=0.35\textwidth}]{2}} {\end{parcolumns}}  \lstnewenvironment{python} {Python \lstset{language=Python,frame=t}} {}  \lstnewenvironment{haskell} {Haskell \lstset{language=Haskell,frame=t}} {}   which is used like that:  \begin{comparison} \colchunk{ \begin{python} A \end{python} } \colchunk{ \begin{haskell} B \end{haskell} } \end{comparison}   I'm still unable to hide \colchunk{} within python or haskell environments. Under , is $\exists x(x=a)$ true in every interpretation in first order logic (FOL) with equality? If so, could $\exists x(x=a)$ be considered a tautology? This question was motivated by  which was closed for lacking clarity. Here I have attempted to add that clarity myself so that the same question can be useful to others who are wondering a similar thing. This is a self answer question. LIM is cofinal in ON I'd like to show that the class of all limit ordinals, LIM, is cofinal in the class of all ordinals ON.  I thought that I could do this by contradiction and assume that it wasn't cofinal in ON. Then there is an $\alpha \in$ ON such that for all $\beta \in $ LIM: $\beta &lt; \alpha$, i.e. $\beta \in \alpha$ and hence LIM $\subset \alpha$.  This means that LIM is a set so we can consider $\bigcup$ LIM. Then we have $\beta &lt; \bigcup$ LIM for all $\beta \in$ LIM by definition of $\bigcup$ LIM. So LIM $\subseteq \bigcup$ LIM.   $\bigcup$ LIM is either a limit or a successor ordinal.  If it is a limit ordinal then $\bigcup$ LIM $\in$ LIM and by transitivity of ON, $\bigcup$ LIM $\subseteq$ LIM, so $LIM = \bigcup$ LIM in this case which would mean that $\bigcup$ LIM $\in$ LIM $= \bigcup$ LIM which would be a contradiction because sets cannot contain themselves. Hence $\bigcup$ LIM cannot be a limit ordinal.  If $\bigcup$ LIM is a successor ordinal then $\bigcup$ LIM = $\beta \cup \{&#160;\beta \}$ for some $\beta \in $ ON.  Now I'm not sure how to proceed from here. I'm also not sure about whether I'm on the right track with this proof because I think there should be a shorter way  to prove this.  Thanks for your help. How to make the BibTeX reference list visible in a LaTeX document Im very new at LaTeX and I would appreciate some help solving this problem. I have created a BibTeX file containing all references to a document. In this text file BibTeX items are inserted and no other text are written, for instance @article{...}. When I call for this bib file from the main.tex file I use the commands:  \bibliographystyle{plain} \bibliography{thebibliography}   Now to my question. All i get when I compile this main.tex is the title (bibliography) for this chapter, otherwise the textfield is blank. Is this error occurring because I should write anything in the bib file or have I missed any lines in the main.tex file. Intersection and union of simply connected domain I have some basics concept that, in $\mathbb{C}$, a "simply connected domain $D$" is a region in $\mathbb{C}$ with no holes. I am not sure whether it has various formal definition , but the one used in my complex analysis class looks very complicated. I barely understand what it means :  $\textbf{Definition}$ Let $\gamma_0, \gamma_1$ be two continuous closed path in a domain $D \subseteq \mathbb{C}$ parameterized by $I = [0,1]$;that is, $\gamma_i(0) = \gamma_i(1)$ for all $i = 0, 1.$ We say $\gamma_0, \gamma_1$ are $\textbf{homotopic as closed paths on D}$ if there exists function $\delta : I \times I \rightarrow D$ such that   $1) \ \delta(t,0) = \gamma_0(t) \ \forall t \in I \ \ $    $2) \ \delta(t,1) = \gamma_1(t) \ \forall t \in I \ \ $     $3) \ \delta(0,u) = \delta(1,u) \ \forall u \in I.$  A continuous closed path is $\textbf{homotopic to a point}$ if it is homotopic to a constant path(as a closed path).  $\textbf{Definition}$ A region $D \subseteq \mathbb{C}$ is called $\textbf{simply conected}$ if every continuous closed path in $D$ is homotopic to a point in $D$.  $\textbf{Problem :}$ 1) Let $D_1, D_2$ be simply connected plane domains whose intersection is nonempty and connected. Prove that their intersection and union are both simply connected.  2) Let $P, Q$ be smooth functions on a domain $D \subseteq \mathbb{C}$, Find necessary and sufficient condition for the form $P dz + Q d\bar{z}$ to be closed.