How to fix this AWT-EventQueue-0 exception
What is a NullPointerException, and how do I fix it?
Air gap on isolation space The below photo belongs to a PSU. I wonder what was the reason of placing air gaps on the 8 mm isolation. Is it to improve the isolation or provide a thermal relief (although there is no component below the red circled air gap)? Salesforce lightning get current users username How I would go about getting the current users username or first and last name?  I have been looking at this for the last couple of hours - I was just wondering how I would go about getting their name and then displaying it on the page.  For example the current user is 'John Smith' and in the lightning component I want to output John Smith's name like:     Welcome to our community John Smith! There is this puzzling thing that is called : paradoxically, warm (35°C) water freezes faster than cold (5°C) water.  As a physisist, I've been asked about it several times already. And I have no definite answer to that, apart from the standard: "there are many things that can influence it".  So, does anyone knows about the status or progress on that effect? Any recent reviews, publications or other references? In column B I have contact number. I want to add a country code to all of them.  For example, if the number is 123456, I want it to become 88123456.    Each number is in 1 row, and there are about a thousand of them, so I want an automatic way to do this that allows me to add the country code to each of them without a space. I've installed Xcode and MacPorts on a brand new mid-2013 MacBook Air, but MacPorts doesn't work, saying that it cannot find anything.  mba:~ cnst$ sudo port install wget Warning: The Command Line Tools for Xcode don't appear to be installed; most ports will likely fail to build. Warning: See http://guide.macports.org/chunked/installing.xcode.html for more information. ---&gt;  Computing dependencies for wgetError: Unable to execute port: can't read "build.cmd": Failed to locate 'make' in path: '/opt/local/bin:/opt/local/sbin:/bin:/sbin:/usr/bin:/usr/sbin' or at its MacPorts configuration time location, did you move it? mba:~ cnst$   And, indeed, there is no make or clang in the path, but it is definitely installed, though:  mba:~ cnst$ find /Applications -name "clang" -or -name "make" /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/clang /Applications/Xcode.app/Contents/Developer/usr/bin/make mba:~ cnst$   Why is there no make or clang in the path?  Why MacPorts doesn't work?  I notice that  mentions that you have to install something from ADC, Apple Command Line Developer Tools, but ADC doesn't work since last Thursday or Friday due to their security breach, so, the developer tools are nowhere to be found.  What's the proper solution here? This one never ceases to confuse me. When to use 'such as' and when to use 'like' while giving examples? Is there any clear rule?        Metros like Mumbai, Delhi and Karachi are unsafe after dark.    Metros such as Mumbai, Delhi and Karachi are unsafe after dark.       (Before anyone points out, Delhi and Karachi are unsafe round-the-clock, but it's just an example.) All operating systems freeze sometimes, and Ubuntu is no exception. What should I do to regain control when...   just one program stops responding? nothing at all responds to mouse clicks or key presses? the mouse stops moving entirely? I have an    In what order should I try various solutions before deciding to pull the power plug?  What should I do when starting up Ubuntu fails?  Is there a diagnostic procedure I can follow? Can I get US sales taxes refunded for electronics purchased while on vacation? I'm visiting the US for vacations (specifically Manhattan) and wanted to buy a digital camera.  The guy at the shop told me that I can get back what I pay in NYC taxes for that camera if I present the ticket at the airport, when I'll be returning home. And that this is not applicable to clothes but it does to electronic stuff.   Is any of this true? Automatically growing lists as in MATLAB? shade plane with a color function color(x,y) I am currently writing my bachelor thesis and I am using LyX as my standard writing program (because I am not familiar with LaTeX at all).  For my bibliographystyle I use JabRef and the citation style needs to be Journal of Finance.  Now, I found this .bst file for the Journal of Finance style online () which is actually really good. But the problem is, that I need it in German. There must be an "und" instead of "and" and all the umlauts don't work as well. Basically I need everything in German.  Do you know a website with a German .bst file? Or can I change something in the settings in LyX or JabRef and everything would be fixed? Are software titles italicized? The titles of freestanding works (books, movies, plays, albums, etc.) are italicized; smaller parts within these works (chapters in a book, articles in a magazine, songs within an album) are not (they are put in quotes, instead).  How are software titles treated?  My understanding is that if a particular program resembles a book or a dramatic work (like a video game), its title is italicized -- otherwise, it is treated as a proper noun, just like any other product.     I played Grand Theft Auto, instead of reading "Democracy in Ancient Greece" in Microsoft Encarta and preparing my presentation in PowerPoint.   Is this approach correct? How do i prove invertibility of this linear transformation Let $T$ be a linear transformation from a vector space $V$  over reals into $V$ such that $T-T^2=I$. Show that $T$ is invertible I notice that the space between each column of a table in LaTeX is not quite wide (at least for me). Is there any way to set this? I found the \hspace, but I don't get how to use this in the table. Problem:   Prove that a set of nine consecutive integers cannot be partitioned into two subsets with same product   My attempt:  This problem would be solved if it could be proven that 9 consecutive numbers cannot exist such that all the numbers are of the form $2^a  3^b  5^c  7^d$ where $a,b,c,d$ are integers.  A suitable hint would be appreciated, I don not want a complete solution.  Edit:  If there existed a prime factor greater than $7$ of any number present in the set, then its multiple cannot exist b/c $22-11&gt;9$  Edit 2: As mentioned by Erick, my reasoning is not valid for numbers $1-9$ and $2-9$, let this be an exception. Can the Telekinesis spell be used to manipulate liquids? $\delta$ differential notation Various textbooks that I am currently consulting (including Spacecraft Dynamics and Control An Introduction - Anton H.J. De Ruiter | Christopher J. Damaren | James R. Forbes Section 1.4, page 32) use $\delta$, not $d$ or $\partial$ to express an infinitesimal quantity. In the context of the reference text above, the symbol is used as part of a general definition for the derivative of a vector. Specifically, given   $$\mathbf{\vec{r}}=\mathcal{\vec{F^{T}_{1}}}\mathbf{\vec{r_{1}}}$$   where   $$\mathcal{\vec{F^{T}_{1}}}$$   is a vectrix   $$[\mathbf{\vec{x_1}} \phantom{s} \mathbf{\vec{y_1}} \phantom{s} \mathbf{\vec{z_1}}].$$  The time derivative of the vector is defined as   $$\dot{\mathbf{\vec{r}}}\triangleq \lim_{\delta t\to 0}\frac{\delta\mathbf{\vec{r}}}{\delta t}.$$  In this context, what is the difference between $\frac{\delta\mathbf{\vec{r}}}{\delta t}$ and $\frac{d \mathbf{\vec{r}}}{d t}$ ?  Note about thermodynamic use of $\delta$: My understanding is that $\delta$ is used in thermodynamic equations to express path dependence of a scalar quantity such as heat or work. What does it mean in the context of an abstract physical vector? My processor is an Intel Core 2 Duo P8600 (2.40GHz). As far as I know that's a 64-bit processor - I'm a bit confused as the architecture is called AMD 64, is this a generic name given to 64-bit architectures? I've heard of x64 but can't see a release labelled with this. etags and other tags The  tag is a synonym of , and has the description     A program to generate tags for a large project. These tags are usable by the Emacs text editor.   This is inconsistent: tags in that sense are always plural, i.e. etags, never etag.  evidently refers to another concept, .  Should  remain a synonym of , and be about HTTP Etags, and should Emacs etags be tagged +? Or should the synonym be unmade, with HTTP Etags on  and etags on ? How can I capitalize the first letter of each word in a string in Perl?