For example you have a HashMap&lt;String, String&gt;  how can you sort values in the hashmap and print them to console  what would be the best ways to do it?
I am relatively new to Java, and often find that I need to sort a Map&lt;Key, Value&gt; on the values.  Since the values are not unique, I find myself converting the keySet into an array, and sorting that array through array sort with a custom comparator that sorts on the value associated with the key.  Is there an easier way?
Why do electron and proton have the same but opposite electric charge? Integrating Factor Method. Why Can We Set the Constant of Integration to Zero? My textbook gives a demonstration of the use of the integrating factor method for solving first order ordinary differential equations:  $\dfrac{dx}{dt} + p(t)x = r(t)$  $\implies g(t)\dfrac{dx}{dt} + g(t)p(t)x = g(t)r(t)$  $\dfrac{d}{dt}[g(t)x]$  We use the product rule and compare the expression to the left-hand side of the above equation:  $g(t)\dfrac{dx}{dt} + \dfrac{dg}{dt}x = g(t)\dfrac{dx}{dt}+g(t)p(t)x$  $\therefore \dfrac{dg}{dt} = g(t)p(t)$  The above equation is separable.  $\therefore \int\dfrac{dg}{g(t)} = \int p(t) dt$  $\implies ln[g(t)] = \int p(t)dt$  My textbook then says that, "We can set the constant of integration to zero -- any function that satisfies $\dfrac{dg}{dt} = g(t)p(t)$ will do for our purposes". However, it gives no explanation as to why this is the case. Why can we set the constant of integration to zero? Why is any function that satisfied $\dfrac{dg}{dt} = g(t)p(t)$ appropriate for our purposes?  I would greatly appreciate it if people could please take the time to elaborate on this. What is "offset null" in IC 741? What is Offset null in 1st and 5th pin in IC 741 (Op-Amp)? Why it is used, though it is not used in many circuits? Give me explanation regarding the offset null! Why offset voltage was formed in IC 741? Can you get a Windows (AD) username in PHP? I have a PHP web application on an intranet that can extract the IP and host name of the current user on that page, but I was wondering if there is a way to get/extract their Active Directory/Windows username as well. Is this possible? The set of all finite subsets of the natural numbers is countable It's driving me nuts! I just want to transfer one simple file from laptop to server.  I'm using ubuntu on both machines.  So I have:  -rwxr-xr-x 1 sandro    414622 2011-10-14 23:42 sandrophoto-html.tar.gz   And I'm sending it using:  sudo scp -P XXXX sandrophoto-html.tar.gz usern@server.local:/media/xx/xx/xx   And I get: scp: /media/xx/xx/xx/sandrophoto-html.tar.gz: Permission denied  p.s. I might be doing this other way around - I want to send file tar.gz that is located on my desktop, to remote server into the folder /media/yadayda Add a time limit before you can vote on a post There needs to be a timer or something on upvoting/downvoting.  I posted an answer to a question and as soon as the page loaded, my answer was already down voted. There is no way someone had the time to read the answer &lt; 10 seconds after it was posted. How might the weight of a falling object affect the damage it causes? Fall damage is 1d6 per 10 feet. What adjustments if any should I make for objects falling on a player character? (e.g. a bear)  Assuming the objects are meaningful threats but not instant character death, should the weight of an object change the calculation, e.g. more then 1d6 per 10 feet.  Or is this more in the spirit of improvising damage chart? i.e. the setback (cat to face) dangerous (orc fell on me), and deadly (the large bear).  If this is house-rule territory does any one have any experience or advice beyond  relevant to 5e. Where is the dimensions option? Supremum and infimum of sets I've recently started to study supremum and infimum, and I'm having trouble determining the supremum and infimum of the following sets:  $ A = \left\{ {mn\over 1+ m+n} \mid m, n \in \mathbb N \right\} $ $ B = \left\{ {mn\over 4m^2+m+n^2} \mid m, n \in \mathbb N \right\} $ $ C = \left\{ {m\over \vert m\vert +n} \mid m \in \mathbb Z, n \in \mathbb N \right\} $ $ D = \left\{ {n\over 3} - \left[{n\over 3}\right] \mid m, n \in \mathbb N \right\} $   In $D$, the $[\; ]$ denotes the integral part of ${n\over 3}$.   $E = \{x \mid x \text{ is decimal fraction between } 0 \text{ and } 1 \text{ that has the digits } 0 \text{ and } 1\}$.  In my progress so far I was able to verify that sup $\{x \in A\} = +∞$  Setting $m = (n-1)$ to get  $$ \frac{mn}{1+m+n}= \frac{n(n-1)}{1 + n + n-1} = \frac{n(n-1)}{2n} = \frac{n-1}{2} $$  That way $\frac{n-1}{2}\in A$ for every $n\geq 2$. Thus, the supremum of $A$ is bigger than $\frac{n-1}{2}$ for every integer $n$.  I don't know how to go past this. x_x  Any help would be greatly appreciated! When I entered the -al attribute with the  command, I got the following:  anupam@JAZZ:~/blog$ ls -al total 76 drwxrwxr-x 13 anupam anupam 4096 Aug 28 21:45 . drwxr-xr-x 34 anupam anupam 4096 Aug 28 20:52 .. drwxrwxr-x  8 anupam anupam 4096 Aug 28 12:19 app drwxr-xr-x  2 anupam anupam 4096 Aug 28 12:19 bin drwxrwxr-x  5 anupam anupam 4096 Aug 28 12:19 config -rw-rw-r--  1 anupam anupam  154 Aug 28 12:19 config.ru drwxrwxr-x  3 anupam anupam 4096 Aug 28 12:37 db -rw-rw-r--  1 anupam anupam 1339 Aug 28 12:19 Gemfile -rw-rw-r--  1 anupam anupam 2871 Aug 28 12:19 Gemfile.lock drwxrwxr-x  7 anupam anupam 4096 Aug 28 21:45 .git -rw-rw-r--  1 anupam anupam  466 Aug 28 12:19 .gitignore drwxrwxr-x  4 anupam anupam 4096 Aug 28 12:19 lib drwxrwxr-x  2 anupam anupam 4096 Aug 28 12:29 log drwxrwxr-x  2 anupam anupam 4096 Aug 28 12:19 public -rw-rw-r--  1 anupam anupam  249 Aug 28 12:19 Rakefile -rw-rw-r--  1 anupam anupam  478 Aug 28 12:19 README.rdoc drwxrwxr-x  8 anupam anupam 4096 Aug 28 12:19 test drwxrwxr-x  6 anupam anupam 4096 Aug 28 12:33 tmp drwxrwxr-x  3 anupam anupam 4096 Aug 28 12:19 vendor   What does each column mean, and what does the total 76 signify here? Feed can show entries for deleted posts, which viewing them fails Related posts:    These posts are different from mine in that they merely ask for the &quot;votes&quot; tab back or ask if it is at all possible to get such information, while I propose how to implement this as a search feature. Background I recently found myself facing a problem very similar to one that I had solved before. I remembered that I found the solution on SO and I remembered upvoting the post containing the solution. I wasn't able to find that particular post by just searching with relevant keywords. It would have been nice if I could search only among the questions I have voted on. I searched on meta and found that there had been a tab for looking at what you've voted on, but that it was removed due to lack of interest. This is understandable, since just listing the hundreds/thousands of posts you've voted on isn't particularly useful. Proposal What I want is to be able to search for posts I've voted on similarly to the way I'm able to search on my posts within a specific tag. For instance: user:310121 [iphone] apple  This will return all my posts tagged iPhone, where I mention Apple. This is brilliant. This is just how I want search to work. Now what I want to do is to extend this to include votes. The exact syntax isn't relevant, but I had to make one up to show you what I mean: To show all posts you've voted on: user:310121 {votes}  To show all posts you've upvoted: user:310121 {upvotes}  To show all posts you've downvoted: user:310121 {downvotes}  You could probably omit the the user part, since you're only allowed to see your own votes. (Unless it's desirable to be able to look at other peoples votes. Maybe you should be allowed to do this if you have enough rep? Well, that's another discussion.) I guess that even if you're allowed to see other peoples votes it would make sense to display your own votes if the user part is omitted. So in my case I could have done the following search and found the post I was looking for: {upvotes} keyword  Lastly I just want to suggest that clicking on your vote count will work just like clicking on a tag. If I click on a tag in my profile the following search will be done: user:310121 [tag]  So if I click on my upvote count the following search should be made: user:310121 {upvotes}  The same goes for downvotes: user:310121 {downvotes}  This would be a very useful feature and it wouldn't be intrusive in any way. The users that don't care for this feature might never know that it's there. And just for the record the favorite system doesn't replace this feature. How to only substitute lines that match several patterns in sed? $ echo -e 'CH12\nCH23au' | sed '/^CH/s=^=&lt;b&gt;=' &lt;b&gt;CH12 &lt;b&gt;CH23au   I know I can match lines starting with CH by ^CH but how can I match multiple patterns?   Example:  Input:  CH12 CH23au   Output:  CH12 &lt;b&gt;CH23au   How to only put &lt;b&gt; where there is ^CH and au in the line? Undecidable language problems. Margin on child element moves parent element Consider the infinite line, $L$ in $2D$ consisting of all points $p$ such that $p.[0.3511 0.9263]= 6$. Find the point on the line closest to $(10, 20)$. Find the point on the line closest to $(4, 3)$. Find the distance from the line to both of these points.  Hi, I was reading the book $3D$ Maths Primer for Graphics and Game Development. The book mention about $2$ formulas but I don't know how to apply them.   $\text{Signed distance} = d-q.n$  $q' = q + (d-q.n)n$  for any point $q$, the point $q'$ that is the closest point on $L$ to $q$.  This is what I have tried,   Since the lines are parallel then the normal are the same so   $q' = q + (6 - q(0.3511 0.9263))(0.3511 0.9263)$   I'm stuck here. How does the Adam method of stochastic gradient descent work? How to pass parameters to an alias? How can a structure have infinite length and infinite surface area, but have finite volume?