What is the difference between 'super' and 'extends' in Java Generics
Difference between  and  in Java
When I search for Chromium in Ubuntu Software on Ubuntu 16.04, There are 2 options.    Which one should I select?    The same can be observed with , ,  etc. This question has an inverse:     What would be the most efficient way to translate a combination of $k$-tuple into its positions within the $\left(\!\!\binom{n}{k}\!\!\right)$ combinations? I need this to be fast for combinations of $\left(\!\!\binom{70}{7}\!\!\right)$ order of magnitude - very large, but not exceeding 2 billion (fits into int32 maximum value).  Below is an example of $\left(\!\!\binom{6}{3}\!\!\right)$, where the aim is to quickly translate (a, d, f) tuple to value 9, while in the real problem $k$ ranges between 5 and 8.  $$\begin{array} {cccccc|c} a&amp;b&amp;c&amp;d&amp;e&amp;f&amp;^{combination}/_{sort\_order}&amp; \\\hline x&amp;x&amp;x&amp; &amp; &amp; &amp;1\\ x&amp;x&amp; &amp;x&amp; &amp; &amp;2\\ x&amp;x&amp; &amp; &amp;x&amp; &amp;3\\ x&amp;x&amp; &amp; &amp; &amp;x&amp;4\\ x&amp; &amp;x&amp;x&amp; &amp; &amp;5\\ x&amp; &amp;x&amp; &amp;x&amp; &amp;6\\ x&amp; &amp;x&amp; &amp; &amp;x&amp;7\\ x&amp; &amp; &amp;x&amp;x&amp; &amp;8\\ x&amp; &amp; &amp;x&amp; &amp;x&amp;9\\ x&amp; &amp; &amp; &amp;x&amp;x&amp;10\\ .&amp;.&amp;.&amp;.&amp;.&amp;.&amp;.\\  &amp; &amp; &amp;x&amp;x&amp;x&amp;20\\ \end{array}$$  I know that I could pre-calculate all the combinations and reverse the lookup dictionary. However, such dictionary would not be efficient in terms of memory usage. Therefore I am looking for either calculation-based approach, or a more efficient data structure to perform this mapping. Does a List guarantee that items will be returned in the order they were added? Does a List&lt;T&gt; always guarantee that items will be returned in the order they were added when enumerated?  Updated: Thanks for all the answers folks, puts my mind at ease. I had a quick poke around the List&lt;T&gt; class with .NET Reflector (should've probably done that in the first place) and indeed the underlying store is an array of T (T[]). Increasing Flood Plain I am doing a project where we are attempting to determine how many more buildings would flood if the FEMA flood plain increased by 1',2' and 5'. I have the elev of the flood plain rasters from lidar data, but I am having trouble figuring out how much more area will be inundated by the rises I described earlier. I'm using raster calc and I have a buffer for the flood plain that also has elevation data. Any thoughts? Mapping building to only one grid which contains more than half of its area using QGIS? I'm completely new and lost in Ubuntu 12.04, I'm having trouble navigating to my Sublime folder which I know is in my /opt folder. Yet I've tried to no avail to navigate into it via Terminal window. The directory is colored in blue, no idea what this means...but I am able to access the folder using the GUI explorer...?  k@k-Ubuntu:~$ cd /opt k@k-Ubuntu:/opt$ ls Sublime Text 2 k@k-Ubuntu:/opt$ cd Sublime Text 2 bash: cd: Sublime: No such file or directory k@k-Ubuntu:/opt$ cd /Sublime Text 2 bash: cd: /Sublime: No such file or directory Why don't Jedi (or Sith) use the Force to snap their foes' necks? I understand that the Jedi use the Force for self defence, but still, couldn't they just use the Force to snap their foes' necks and be done with it? Like when Jaina Solo was hunting down Darth Caedus. Or even when Caedus was duelling Grand Master Skywalker. If he just used the Force to snap Skywalker's neck (like he did to poor Lieutenant Tebut), it will all be over very fast.  Is there a canon reason why Jedi and Sith don't use their powers to directly harm their opponents? How should you interview for QA *Automation* positions? How to report that a question should be migrated to another site? How can I require a generic parameter to be an enum that implements an interface? @future method: Unsupported parameter type I am trying to copy records from one org to other via web services. I am calling a class which has logic written into a trigger. But @ future method is not taking sObject  list as a parameter. Can someone suggest me an alternative?  The Code:  public class webServicesTriggerClass   {     @future public static void webServicesMethod(list&lt;MyFriend__c&gt; mfList)     {         partnerSoapSforceCom.Soap sp = new partnerSoapSforceCom.Soap();       partnerSoapSforceCom.LoginResult lr = sp.login('hitesh.kumar.singh@accenture.com.varun','4Rajyavardhan');      soapSforceComSchemasClassNiralaapp.SessionHeader_element ses = new soapSforceComSchemasClassNiralaapp.SessionHeader_element();      ses.sessionId = lr.sessionId;       soapSforceComSchemasClassNiralaapp.MyFriendsDetailSoapApi vNapp=new soapSforceComSchemasClassNiralaapp.MyFriendsDetailSoapApi();      for(MyFriend__c mf:mfList)       {        string  s1= mf.myEmail__c;        string  s2=mf.friendName__c;         string  s3=mf.friendEmail__c;        string  s4=mf.aboutFriend__c;        integer i1=Integer.ValueOf(mf.age__c);        boolean result=vNapp.addFriendDetails(s1,s2,s3,s4,i1);        system.debug('################' +result);           }     }    }     Trigger-->  trigger webServicesTrigger on MyFriend__c (after insert)     {      webServicesTriggerClass.webServicesMethod(trigger.new);    }     Error--    Error: Compile Error: Unsupported parameter type LIST at line 3 column 30 Ways to go from A to B(proof) Capitalization of explanation of abbreviations A friend wants to use my account for a wire transfer. Is this a scam or is it legitimate? I have a friend since July online and Exxon owe him for a balance on a 2014 contract off the shores of Liverpool. He is presently in the Gulf of Mexico completing a contract that last for one year. During that year he cannot get off the boat there fore he cannot receive the money.  Exxon has notified him that his check has been deposited in Samba Bank in London. If he doesn’t receive his money within two weeks it goes back to Exxon and he said that there I not telling nohow long before he will receive the money again. He said that with him being off shore that he needs me to be his beneficiary to receive the money for him. He wants me to keep the money in my account and when he gets off the boat in 6 weeks he is relocating to where I live.  I am to buy a house before he gets here and then he wants us to start a business together. He talked with me for quite a while before he told me how much he makes. He knows I do not have any money to mention. I have stock in a formal shop but not any money.  He said if this money had not come in when it did he would have had to postpone his plan until he gets paid what Shell Oil owes him for this contract that he will finish October 15th. He said he had given enough of his life to the gas and oil industry and is not going to sign another contract.  What do you think about the safety of this? I have calculated AIC and AICc to compare two general linear mixed models; The AICs are positive with model 1 having a lower AIC than model 2.  However, the values for AICc are both negative (model 1 is still &lt; model 2).  Is it valid to use and compare negative AICc values? Scatterplot with too many points What does $\rightarrow$ mean in $p \rightarrow q$ I was looking at an exercise where it asked the following:  $$\begin{array}{ccc} p&amp;q&amp;p\rightarrow q \\ T&amp;T&amp;T \\ &amp;\ldots \end{array}$$  So, for the third column, I just put $T$ which was correct but I didn't understand what $\rightarrow$ meant. I have seen $\implies$ but I haven't the arrow. Are they the same thing?  Thanks a bunch! How to recover data from a failing hard drive? An external 3½" HDD seems to be in danger of failing — it's making .  I've acquired a replacement drive, and want to know the best strategy to get the data off of the dubious drive with the best chance of saving as much as possible.  There are some directories that are more important than others.  However, I'm guessing that picking and choosing directories is going to reduce my chances of saving the whole thing.  I would also have to mount it, dump a file listing, and then unmount it in order to be able to effectively prioritize directories.  Adding in the fact that it's time-consuming to do this, I'm leaning away from this approach.  I've considered just using dd, but I'm not sure how it would handle read errors or other problems that might prevent only certain parts of the data from being rescued, or which could be overcome with some retries, but not so many that they endanger other parts of the drive from being saved.  I guess ideally it would do a single pass to get as much as possible and then go back to retry anything that was missed due to errors.  Is it possible that copying more slowly — e.g. pausing every x MB/GB — would be better than just running the operation full tilt, for example to avoid any overheating issues?  For the "where is your backup" crowd: this actually is my backup drive, but it also contains some non-critical and bulky stuff, like music, that aren't backups, i.e. aren't backed up.  The drive has not exhibited any clear signs of failure other than this somewhat ominous sound.  I did have to fsck a few errors recently — orphaned inodes, incorrect free blocks/inodes counts, inode bitmap differences, zero dtime on deleted inodes; about 20 errors in all.  The filesystem of the partition is ext3. Block quote with big quotation marks Selected references without hyperlink When using the hyperref package, is it possible to tell LaTeX not to create a link for some references?  In my case the page number is displayed in the footer in  \fancyhf[FC]{\thepage\ of \pageref{pg:end}}   which is what I want. Unfortunately every single page in the document then has a link to the final page, which is a bit silly.  Any ideas on how to fix that?