&gt; NOTE:  This question is from 2014.  As of Java 11 OpenJDK and Oracle
&gt; JDK are converging.

Are there any crucial differences between Oracle and OpenJDK?

For example, are the garbage collection and other JVM parameters the same?

Does GC work differently between the two?


Differences between Oracle JDK and OpenJDK

What is the difference between **JVM**, **JDK**, **JRE** &amp; **OpenJDK**?

I was programming in Java and I encountered these phrases, what are the differences among them?

What is the difference between JVM, JDK, JRE &amp; OpenJDK?

I saw the `ViewBag` in MVC 3. How&#39;s that different than `ViewData` in MVC 2?

What&#39;s the difference between ViewData and ViewBag?

I am trying to calculate the difference between two `LocalDateTime`. 

The output needs to be of the format `y years m months d days h hours m minutes s seconds`. Here is what I have written:

    import java.time.Duration;
    import java.time.Instant;
    import java.time.LocalDateTime;
    import java.time.Period;
    import java.time.ZoneId;
    
    public class Main {
    
    	static final int MINUTES_PER_HOUR = 60;
    	static final int SECONDS_PER_MINUTE = 60;
    	static final int SECONDS_PER_HOUR = SECONDS_PER_MINUTE * MINUTES_PER_HOUR;
    
    	public static void main(String[] args) {
    		LocalDateTime toDateTime = LocalDateTime.of(2014, 9, 9, 19, 46, 45);
    		LocalDateTime fromDateTime = LocalDateTime.of(1984, 12, 16, 7, 45, 55);
    		
    		Period period = getPeriod(fromDateTime, toDateTime);
    		long time[] = getTime(fromDateTime, toDateTime);
    		
    		System.out.println(period.getYears() + &quot; years &quot; + 
    				period.getMonths() + &quot; months &quot; + 
    				period.getDays() + &quot; days &quot; +
    				time[0] + &quot; hours &quot; +
    				time[1] + &quot; minutes &quot; +
    				time[2] + &quot; seconds.&quot;);
    
    		
    	}
    
    	private static Period getPeriod(LocalDateTime dob, LocalDateTime now) {
    		return Period.between(dob.toLocalDate(), now.toLocalDate());
    	}
    
    	private static long[] getTime(LocalDateTime dob, LocalDateTime now) {
    		LocalDateTime today = LocalDateTime.of(now.getYear(),
    				now.getMonthValue(), now.getDayOfMonth(), dob.getHour(), dob.getMinute(), dob.getSecond());
    		Duration duration = Duration.between(today, now);
    
    		long seconds = duration.getSeconds();
    
    		long hours = seconds / SECONDS_PER_HOUR;
    		long minutes = ((seconds % SECONDS_PER_HOUR) / SECONDS_PER_MINUTE);
    		long secs = (seconds % SECONDS_PER_MINUTE);
    
    		return new long[]{hours, minutes, secs};
    	}
    }

The output that I am getting is `29 years 8 months 24 days 12 hours 0 minutes 50 seconds`. I have checked my result from this [website][1] (with values `12/16/1984 07:45:55` and `09/09/2014 19:46:45`). The following screenshot shows the output:

![Epoch Converter][2]

I am pretty sure that the fields after the month value is coming wrong from my code. Any suggestion would be very helpful.

Update
-
I have tested my result from another website and the result I got is different. Here it is: [Calculate duration between two dates][3] (result: 29 years, 8 months, 24 days, 12 hours, 0 minutes and 50 seconds).

Update
-
Since I got two different results from two different sites, I am wondering if the algorithm of my calculation is legitimate or not. If I use following two `LocalDateTime` objects:

    LocalDateTime toDateTime = LocalDateTime.of(2014, 9, 10, 6, 40, 45);
    LocalDateTime fromDateTime = LocalDateTime.of(1984, 12, 16, 7, 45, 55);

Then the output is coming: `29 years 8 months 25 days -1 hours -5 minutes -10 seconds.`

From this [link][4] it should be `29 years 8 months 24 days 22 hours, 54 minutes and 50 seconds`. So the algorithm needs to handle the negative numbers too.

**Note the question is not about which site gave me what result, I need to know the right algorithm and need to have right results.**


  [1]: http://www.epochconverter.com/epoch/date-difference.php
  [2]: http://i.stack.imgur.com/SAJE4.png
  [3]: http://www.timeanddate.com/date/durationresult.html?d1=16&amp;m1=12&amp;y1=1984&amp;d2=9&amp;m2=9&amp;y2=2014&amp;h1=7&amp;i1=45&amp;s1=55&amp;h2=19&amp;i2=46&amp;s2=45
  [4]: http://www.timeanddate.com/date/durationresult.html?d1=16&amp;m1=12&amp;y1=1984&amp;d2=10&amp;m2=9&amp;y2=2014&amp;h1=7&amp;i1=45&amp;s1=55&amp;h2=6&amp;i2=40&amp;s2=45

Java 8: Difference between two LocalDateTime in multiple units

What is the difference between memoization and dynamic programming? I think dynamic programming is a subset of memoization. Is it right?

What is the difference between memoization and dynamic programming?

I know I can do anything and some more envolving Dates with momentjs. But embarrassingly, I&#39;m having a hard time trying to do something that seems simple: geting the difference between 2 times.

Example:

    var now  = &quot;04/09/2013 15:00:00&quot;;
    var then = &quot;04/09/2013 14:20:30&quot;;

    //expected result:
    &quot;00:39:30&quot;

what I tried:

    var now = moment(&quot;04/09/2013 15:00:00&quot;);
    var then = moment(&quot;04/09/2013 14:20:30&quot;);
    
    console.log(moment(moment.duration(now.diff(then))).format(&quot;hh:mm:ss&quot;))
    //outputs 10:39:30  

I do not understand what is that &quot;10&quot; there. I live in Brazil, so we are utc-0300 if that is relevant.

The result of `moment.duration(now.diff(then))` is a duration with the correct internal values:  

     days: 0
     hours: 0
     milliseconds: 0
     minutes: 39
     months: 0
     seconds: 30
     years: 0

So, I guess my question is: how to convert a momentjs Duration to a time interval? I sure can use

    duration.get(&quot;hours&quot;) +&quot;:&quot;+ duration.get(&quot;minutes&quot;) +:+ duration.get(&quot;seconds&quot;)

but i feel that there is something more _elegant_ that I am completely missing.

**update**  
looking closer, in the above example `now` is:  
 
    Tue Apr 09 2013 15:00:00 GMT-0300 (E. South America Standard Time)…}
and `moment(moment.duration(now.diff(then)))` is:

    Wed Dec 31 1969 22:39:30 GMT-0200 (E. South America Daylight Time)…}

I am not sure why the second value is in Daylight Time (-0200)... but I am sure that i do not like dates :(

**update 2**  

well, the value is -0200 probably because 31/12/1969 was a date where the daylight time was being used... so thats that.

Get the time difference between two datetimes

The **bottom-up** approach (to dynamic programming) consists in first looking at the &quot;smaller&quot; subproblems, and then solve the larger subproblems using the solution to the smaller problems.

The **top-down** consists in solving the problem in a &quot;natural manner&quot; and check if you have calculated the solution to the subproblem before.

I&#39;m a little confused. What is the difference between these two?

What is the difference between bottom-up and top-down?

How can I get the difference between two images? I have the original image. Someone has written on an exact duplicate of the original image. Now, I need to compare the original to the written on image and extract just the writing in image format.

Example: I have a picture of a house. Someone took a copy and wrote “Hello!” on the copy. I want to somehow compare the two pictures, remove the house, and be left with an image of the words “Hello!”.

Is this possible with ImageMagick? I know there are ways to get the statistical difference between images, but that is not what I am looking for.

“Diff” an image using ImageMagick

Can you explain what is the difference between `HashSet&lt;T&gt;` and `List&lt;T&gt;` in .NET? 

Maybe you can explain with an example in what cases `HashSet&lt;T&gt;` should be preferred against `List&lt;T&gt;` ?


What is the difference between HashSet&lt;T&gt; and List&lt;T&gt;?

What are differences between these commands in C#

    string text= &quot;  &quot;;
    1-string.IsNullOrEmpty(text.Trim())

    2-string.IsNullOrWhiteSpace(text)

Difference between IsNullOrEmpty and IsNullOrWhiteSpace in C#

I&#39;ve been using **Git Extensions** for a while now (it&#39;s awesome!) but I haven&#39;t found a simple answer to the following:

Sometimes, when typing a commit message, a make a typo. My friend showed me how to fix it the following way (in Git Extentions):

&gt; Right-Click on the commit &gt; Advanced &gt; Fixup commit

![enter image description here][1]

Then I simply check the box &quot;Amend&quot; and rewrite my message and voila! My commit message is fixed.

However this other option &quot;Squash commit&quot;... I have always wondered what it does?!

**My question is:**

Would someone simply explain me what is the exact difference between **Squash commit** and **Fixup commit** in **Git/Git Extentions**? They look kind of... *&quot;similar&quot;* to me:
![enter image description here][2]
![enter image description here][3]


  [1]: http://i.stack.imgur.com/XK6Jt.png
  [2]: http://i.stack.imgur.com/qIHAX.png
  [3]: http://i.stack.imgur.com/FFuPd.png

What&#39;s the difference between &quot;squash&quot; and &quot;fixup&quot; in Git/Git Extension?

This is kind of naive question but I am new to NoSQL paradigm and don&#39;t know much about it. So if somebody can help me clearly understand difference between the HBase and Hadoop or if give some pointers which might help me understand the difference.

Till now, I did some research and acc. to my understanding Hadoop provides framework to work with raw chunk of data(files) in HDFS and HBase is database engine above Hadoop, which basically works with structured data instead of raw data chunk. Hbase provides a logical layer over HDFS just as SQL does. Is it correct?




Difference between HBase and Hadoop/HDFS

We have been using just Toasts in our application so far and as we are planning to adopt some new features from Support Design Library I am wondering what&#39;s the recommended usage for Snackbar vs. Toast.

I have been reading on ***[the google material snackbar doc.][1]***

&gt; Snackbars provide lightweight feedback about an operation in a small
&gt; popup at the base of the screen on mobile and at the lower left on
&gt; desktop. They are above all over elements on screen, including the
&gt; FAB.

and toasts.

&gt; Android also provides a capsule-shaped toast, primarily used for
&gt; system messaging. Toasts are similar to snackbars but do not contain
&gt; actions and cannot be swiped off screen.

I understand what they do but I am a bit confused when to use what. Does it mean that:

 - If I don&#39;t require user interaction I would use a toast?
 - What is meant by &quot;system messaging&quot;? Does that apply to displaying information when something important happened between my app and the Android system?
 - What I like is the swipe off screen feature - would that be a reason to start replacing toasts with snackbars? (this is a bit opinion based question though)

  [1]: https://material.io/design/components/snackbars.html#

Android - Snackbar vs Toast - usage and difference

That is the difference between `groupby(&quot;x&quot;).count` and `groupby(&quot;x&quot;).size` in pandas ?

Does size just exclude nil ?

What is the difference between size and count in pandas?

I currently have a user&#39;s profile page that brings out their date of birth and other details. But I am planning to find the days before their birthday by calculating the difference between today&#39;s date and the date of birth obtained from the user.

**User&#39;s Date of Birth**

[![User DOB][1]][1]

And this is today&#39;s date obtained by using the [intl package][2]. 

**Today&#39;s date**

    I/flutter ( 5557): 09-10-2018

The problem I am facing now is, How do I calculate the difference in days of these two dates? 

Are there any specific formulas or packages that are available for me to check out?

  [1]: https://i.stack.imgur.com/0SDZ2.png
  [2]: https://pub.dartlang.org/packages/intl#-installing-tab-

Flutter: Find the number of days between two dates

As per my research, there is a significant difference in the concept of backstack and how they exist:

### Activity


 - When an `activity` is placed to the `backstack` of `activities` the user
   can navigate back to the previous activity by just pressing the `back`
   button.

 - `Activity` can exist independently.

### Fragment

 - When an `fragment` is placed to the activity we have to request the
   instance to be saved by calling `addToBackstack()` during the `fragment`
   `transaction`.

 - `Fragment` has to live inside the `activity`


Are there any additional differences?

What are the differences between activity and fragment?

I don&#39;t quite understand how different they are from each other so I have some inquiries regarding these two packages.

After looking around a bit on Google, it seems like Oracle decided to update the `NIO` package with the newer and enhanced `NIO.2` package as part of the JDK7 release.

1. How does the performance of `NIO` package compare with the `NIO.2` package?
2. What are some big changes from `NIO` to `NIO.2`? (e.g. new methods, features)
3. Why did the original `NIO` package have to be updated?
4. Is `NIO.2` just synonymous with the `NIO` package nowadays? 

It&#39;s not that I want to use the legacy package in my code, I&#39;m just really curious about this. Please tell me their differences?

Java: what exactly is the difference between NIO and NIO.2?

I would like to know (in a few words) what are the main differences between OpenMP and MPI.

What are the differences between MPI and OpenMP?

I have two date like:

    String date_1=&quot;yyyyMMddHHmmss&quot;;
    String date_2=&quot;yyyyMMddHHmmss&quot;;

I want to print the difference like:

    2d 3h 45m

How can I do that? Thanks!

Android difference between Two Dates

I&#39;m new to the topic of neural networks. I came across the two terms _convolutional neural network_ and _recurrent neural network_. 

I&#39;m wondering if these two terms are referring to the same thing, or, if not, what would be the difference between them?

What&#39;s the difference between convolutional and recurrent neural networks?

I&#39;ve just started working with CMake and I noticed that they have both a `find_package` and a `find_library`. And this confuses me. Can somebody explain the difference between a package and a library in the world of programming? Or, in the world of CMake?

Appreciate it, guys!

Package vs Library

I am confused on what&#39;s the difference between them, and which one to choose in which case. Some difference might be obvious, like `any` and `eq`, but I&#39;m including them all just to be sure.

I wonder about their differences because I came across this problem:
I have this POST method in a Controller class

    public Response doSomething(@ResponseBody Request request) {
        return someService.doSomething(request);
    }

And would like to perform a unit test on that controller.
I have two versions. The first one is the simple one, like this

    @Test
    public void testDoSomething() {
        //initialize ObjectMapper mapper
        //initialize Request req and Response res
        
        when(someServiceMock.doSomething(req)).thenReturn(res);

        Response actualRes = someController.doSomething(req);
        assertThat(actualRes, is(res));
    }

But I wanted to use a MockMvc approach, like this one 

    @Test
    public void testDoSomething() {
        //initialize ObjectMapper mapper
        //initialize Request req and Response res
        
        when(someServiceMock.doSomething(any(Request.class))).thenReturn(res);

        mockMvc.perform(post(&quot;/do/something&quot;)
                .contentType(MediaType.APPLICATION_JSON)
                .content(mapper.writeValueAsString(req))
        )
                .andExpect(status().isOk())
                .andExpect(jsonPath(&quot;$message&quot;, is(&quot;done&quot;)));
    }

Both work well. But I wanted my `someServiceMock.doSomething()` in the MockMvc approach to receive `req`, or at least an object that has the same variable values as `req` (not just any `Request` class), and return `res`, just like the first. I know that it&#39;s impossible using the MockMvc approach (or is it?), because the object passed in the actual call is always different from the object passed in the mock. Is there anyway I can achieve that? Or does it even make sense to do that? Or should I be satisfied using `any(Request.class)`? I&#39;ve tried `eq`, `same`, but all of them fail.


What&#39;s the difference between Mockito Matchers isA, any, eq, and same?

I&#39;m currently using a `List&lt;T&gt;` as a queue (use `lst[0]` then `lst.removeAt(0)`) to hold objects.  There&#39;s about 20 items max at a given time.  I realized there was an actual `Queue&lt;T&gt;` class.  I&#39;m wondering if there&#39;s any benefit (performance, memory, etc.) to using a `Queue&lt;T&gt;` over a `List&lt;T&gt;` acting like a queue?

Queue&lt;T&gt; vs List&lt;T&gt;

In simple words, what is the difference between cross-validation and grid search? How does grid search work? Should I do first a cross-validation and then a grid search?

All Difference Solutions on Gang of Coders

Total of 24 Difference Solutions

Differences between Oracle JDK and OpenJDK

What is the difference between JVM, JDK, JRE & OpenJDK?

What's the difference between ViewData and ViewBag?