I've started getting back to java and I have a general question about defining a constructor for an object: I'm following a tutorial where he defines a HashSet object by the following statement:  Set&lt;String&gt; set = new HashSet&lt;String&gt;(list);   (list is a List object)  And I was wondering what's the difference if I use this statement:  HashSet&lt;String&gt; set = new HashSet&lt;String&gt;(list);   thanks!
I have seen this mentioned a few times and I am not clear on what it means. When and why would you do this?   I know what interfaces do, but the fact I am not clear on this makes me think I am missing out on using them correctly.   Is it just so if you were to do:  IInterface classRef = new ObjectWhatever()   You could use any class that implements IInterface? When would you need to do that? The only thing I can think of is if you have a method and you are unsure of what object will be passed except for it implementing IInterface. I cannot think how often you would need to do that.   Also, how could you write a method that takes in an object that implements an interface? Is that possible?
The close dialog says there are two off-topic votes, but none of the off-topic reasons have votes next to them I've found strange behavior when closing this  - I definitely see that there are 3 closing votes and 2 of them are at "Off-topic" section:   -but there are no explanations on section itself:   -while, normally, it's expected that it will appear. In custom comments section there are also no closing-votes displayed.   Perhaps it's just my browser (which is FF 26 x64 under Win) - so marking this as a "possible bug". Thank you for your attention. How to get selected text from textbox control with javascript pgfplots and using axis cs to add points I am trying to mark two inflection points using a foreach loop in a pgfplot, but it isn't working.  \documentclass[tikz]{standalone} \usepackage{pgfplots} \pgfplotsset{compat = 1.10}  \begin{document} \begin{tikzpicture}   \pgfmathsetmacro{\infx}{1/sqrt(2)}   \pgfmathsetmacro{\infy}{exp(-.5)}   \begin{axis}[     xmin = -3,     xmax = 3,     ymin = -0.1,     ymax = 1.05,     domain = -4:4     ]     \addplot[blue, samples = 500, smooth] gnuplot {exp(-x^2)};      \foreach \x/\y in {\infx/\infy, -\infx/\infy}{       \draw[red] (axis cs: \x, \y) circle[radius = .025];     }   \end{axis} \end{tikzpicture} \end{document}   I am being told:  Undefined control sequence.^M &lt;argument&gt; axis cs: \x ^M                        , \y ^M l.34   \end{axis}^M How can I prove that every prime except 2 and 5 divide infinitely many of the following integers $11, 111, 1111, ...$ ? Update all objects in a collection using LINQ Is there a way to do the following using LINQ?  foreach (var c in collection) {     c.PropertyToSet = value; }   To clarify, I want to iterate through each object in a collection and then update a property on each object.  My use case is I have a bunch of comments on a blog post, and I want to iterate through each comment on a blog post and set the datetime on the blog post to be +10 hours. I could do it in SQL, but I want to keep it in the business layer. What is the physical significance of the off-diagonal moment of inertia matrix elements? The tensor of moment of inertia contains six off-diagonal matrix elements, which vanish if we choose a reference frame aligned with the principal axes of the rotating rigid body; the angular momentum vector is then parallel to the angular velocity. But while considering the general case, what are the off-diagonal moment of inertia matrix elements? That is, do they have any physical significance as [say] the components of a vector? Or is it merely a mathematical construction with no definite physical meaning (which seems rather wrong to me)?  A similar thread exists  but they are more interested in the principal axes of the body. It also says:     The physical significance of the off-diagonal components is that   you're using a coordinate system not aligned with the principal   directions of the object. They tell us nothing interesting about the   object itself.   Is that all or is there more to it, perhaps related to properties of tensors in general? What is $\Delta t$ in the time-energy uncertainty principle? In non-relativistic QM, the $\Delta E$ in the time-energy uncertainty principle is the limiting standard deviation of the set of energy measurements of $n$ identically prepared systems as $n$ goes to infinity. What does the $\Delta t$ mean, since $t$ is not even an observable? I have a dual boot laptop (Windows 10). I ran general updates and now my Ubuntu won't boot.   I ran in recovery mode and still it freezes in the same place.      Kernel panic – not syncing: Attempted to kill init! exit code=0x00007f00 How can I convert string to datetime with format specification in JavaScript? Were there any canon examples of Harry being an innately powerful wizard? Was Harry Potter an innately powerful/skillful Wizard in any way, based on canon?  It seems that whenever Harry Potter performed some unusually potent bit of magic (potent as far as require raw power AND/OR skill), most of the time we find that it wasn’t innately Harry’s skill, but a combination of:   some extraneous magic forces/rules/powers circumstance great reaction time (which is obviously extraordinary from his Quidditch playing; and is likely a larger factor in his dueling than the strength of his magic) general smartness or (the part that Harry’s detractors, including Voldemort missed) Harry’s strength of character/personality   The only two counter-examples I can think of which show him as having extraordinary or at least obviously above average magical abilities are:   His skill at flying brooms - while a part of it is pure physical skill, at least part is magical. His (corporeal) Patronus charm   As far as examples of his unusual feats being due to reasons listed above:   Obviously, surviving Avada Kedavra as an infant - due to Lily’s sacrifice Parselmouth talent - proxied via Voldemort’s piece of soul. Ability to see the Sorcerer’s Stone in the Mirror of Erised - due to purity of his character, nothing magical. Obvious lack of talent at potion making throughout all of the books (sans cheating in HBP) His win over the Basilisk - due to Hermione’s research, character traits, and as a consequence of the last one, getting Fawkes and Gryffindor’s Sword’s help.  Just to be clear, before someone flames me - what he did was obviously super extraordinary, BUT IMHO he would have achieved the same result if he was turned into a Squib for the duration of Chamber of Secrets fight. TriWizard Tournament entry - wasn’t him, it was Barty Crouch TriWizard Tournament second challenge - a combination of character and outside help (someone told him about Gillyweed) TriWizard Tournament third challenge - Mostly, Barty Crouch’s cheating  Note that I’m omitting the first challenge, since that one was the aforementioned Broom flying skills. His survival in the cemetery after Voldemort’s return - again, a combination of superior strength of character and super powerful wandlore magic that had nothing to do with his skill as a Wizard. The whole “last Horcrux” thing when surviving the second Avada Kedavra from Voldemort His ownership of the Elder Wand in the very last duel with Voldemort.   So, to paraphrase my original question, was there any canon/JKR evidence that Harry was anything but a completely average/mediocre wizard in any way, shape, or form if you take into account only his own magical abilities and skills? Why is it difficult to differentiate between  and ? Is it because we don't clearly understand how both of these phenomenon takes place?   My thoughts: From an answer to one of my earlier question  I could understand that light waves behave differently when it strikes a slit which is of several times bigger than its wavelength and when it strikes a slit of size comparable to it its wavelength.In the former case the different points on the slit acts as wave-front sources producing circular wave fronts which interfere to form the diffraction pattern but in the later case plane wave-front striking a slit after passing through it forms circular wave-fronts and two such wave-fronts from two different slits interfere to form the interference pattern. But, I'm not satisfied by that because I don't get any intuition about points on the slit acting as wavefront sources. So, what is actually happening? Integrated circuits seem to have standard voltages of 5 V, 3.3 V, 2.5 V, 1.8 V, etc.  Who decides these voltages? Why do smaller devices require lower voltages? I'm trying to factorise $$ x^3z - x^3y - y^3z + yz^3 + xy^3 - xz^3 $$ into four linear factors.  By plugging it into WolframAlpha I've learned that it's $$-(x-y)(x-z)(y-z)(x+y+z)$$  My question is: what are the steps involved in factorising the expression? Is there a method I don't know about that I'd have access to with my limited maths?  Really appreciate any help! Can I use multiple regression when I have mixed categorical and continuous predictors? It looks like you can use coding for one categorical variable, but I have two categorical and one continuous predictor variable. Can i use multiple regression for this in SPSS and if so how? thanks! I'm a software developer and as such I build and run programs hundreds of times per day. I've noticed that since I started using Catalina, after compiling and linking there is a delay (which can be seconds) when the internet is slow or having problems (I have bad internet often). If I disable wifi and rebuild, the delay goes away. How can I disable this so my builds run faster? I came to know about , it's a website that allow search for flights by country. I mean you just enter from like "Germany" and to like "Belgium" and you get best offers from all airports between the two countries. That is great. And I was able to arrange a good-price trip to Brussels.   Now I want to arrange another trip to Turkey, but Whichbudget is not helping much this time. And I can't find any other websites that allow "search by country".   Update: Not duplicate to  as his question is broad to the extent of a state. But my question is broad to the extent of a whole country + less price + "Any Time". If anyone checks , he'll understand what I'm saying. Especially that whichbudget allows "Any Time" option, not just +/-3 days.  Does anyone know more similar websites? Can Minecraft be played by two players locally on the same account? I just bought Minecraft. Now, my brother wants to play with me but my Mom doesn't want to buy another. We use the same Wifi network. Can we do this? Installing Guest Additions causing problems I am trying to install Guest Additions in VirtualBox with Windows XP host and Ubuntu 12.04 guest. I followed the above steps:  Devices-&gt; Insert Guest Additions CD Image. After that I locate the folder /media/VBoxAdditions4.3.4_91027/ and run sudo ./VBoxLinuxAdditions.run   I want to be able to create shared folders and adjust the resolution of the screen. I achieved to do the first issue, but I couldn't do the second one. I didn't get any message, however it is not possible to change the resolution of the screen and I cannot switch to fullscreen. What am I doing wrong?  I found in the instal log the following message: unknown version of the X Window System. I've tried the solution of the proposed link but I got the following message:  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: virtualbox-guest-x11 : Depends: xorg-video-abi-11                     Depends: xserver-xorg-core (&gt;= 2:1.10.99.901) E: Unable to correct problems, you have held broken packages.   I tried also to install with the command sudo apt-get install virtualbox-guest-dkms but nothing is changing. During the installation of dkms I got the message: Error! Bad return status for module build on kernel 3.13.0-32-generic(i686). Print lines between (and including) two patterns I want to start grepping from the lines that has CK at the end of line and stop grepping when the line has D at the end. I tried grep "$CK" "$D" file..txt, but it didn't work.  Input:  kkkkkkkkkkk    jjjjjjjjjjjjjjjjjj   gggggggggggg/CK   JHGHHHHHHHH    HJKHKKLKLLL    JNBHBHJKJJLKKL   JLKKKLLKJLKJ/D   GGGGGGGGGGGGGG   GGGGGGGGGGGGGG   The desired output:  gggggggggggg/CK   JHGHHHHHHHH    HJKHKKLKLLL    JNBHBHJKJJLKKL   JLKKKLLKJLKJ/D I have to prove that if $E$ is a connected space, then so is $\overline{E}$ (the closure of $E$) a connected space. I tried to prove the contrapositive. So suppose that $\overline{E}$ is not connected in a metric space $X$. This implies there are $A\subset X$ and $B\subset X$ such that $A\cap B=\emptyset$, $A\cap \overline{E}\neq \emptyset$, $B\cap \overline{E}\neq \emptyset$ and $\overline{E}\subset A\cup B$. I will try to prove that this $A$ and $B$ will also work for $E$. Suppose that $A\cap E=\emptyset$ and $B\cap E=\emptyset$, this implies that $A\cup B$ is a subset of the limit points of $E$, because $A\cap \overline{E}\neq \emptyset$ and $B\cap \overline{E}\neq \emptyset$. This contradicts the fact that $\overline{E}\subset A\cup B$, so we have to conclude that $A\cap E\neq \emptyset\neq B\cap E$. Since $E\subset\overline{E}\subset A\cup B$, we have that $E$ is also not connected.  My question is whether my proof is correct, because I have a little bit doubt. If it's not correct, what is the best I can do? Thanks in advance!   Edit1: The definition we use for a connected space $E$ in a metric space $X$ is that if $E$ is connected, then there are no open $A,B\subset X$ such that $A\cap B=\emptyset$, $A\cap E\neq \emptyset\neq B\cap E$ and $E\subset A\cup B$.  Edit2: $A$ and $B$ must be open.