[`replace` function][2] in Kotlin has overloads for either raw string and regex patterns.

    &quot;Test  me&quot;.replace(&quot;\\s+&quot;, &quot; &quot;)

This replaces raw string `\s+`, which is the problem.

    &quot;Test  me&quot;.replace(&quot;\\s+&quot;.toRegex(), &quot; &quot;)

This line replaces multiple whitespaces with a single space. 
Note the explicit [`toRegex()`][3] call, which makes a `Regex` from a `String`, thus specifying the overload with `Regex` as pattern.

There&#39;s also an overload which allows you to produce the replacement from the matches. For example, to replace them with the first whitespace encountered, use this:

    &quot;Test\n\n  me&quot;.replace(&quot;\\s+&quot;.toRegex()) { it.value[0].toString() }

&lt;hr&gt;
By the way, if the operation is repeated, consider moving the pattern construction out of the repeated code for better efficiency:

    val pattern = &quot;\\s+&quot;.toRegex()
    
    for (s in strings)
        result.add(s.replace(pattern, &quot; &quot;))


  [1]: https://kotlinlang.org/docs/reference/basic-types.html#characters
  [2]: https://kotlinlang.org/api/latest/jvm/stdlib/kotlin.text/replace.html
  [3]: https://kotlinlang.org/api/latest/jvm/stdlib/kotlin.text/to-regex.html

I&#39;m using MongoRepository in spring boot to access mongo:

    public interface MongoReadRepository extends MongoRepository&lt;User, String&gt; {
        @Query(value = &quot;{$where: &#39;this.name == ?0&#39;}&quot;, count = true)
        public Long countName(String name);
    }
and it could work, but i wonder know the exactly query it accessing mongo

how to do that?

i try to adding some config at properties like below:

    logging.level.org.springframework.data.mongodb.core.MongoTemplate=DEBUG
    logging.level.org.springframework.data.mongodb.repository.Query=DEBUG

and don&#39;t work.

could somebody help?

how to show query while using query annotations with MongoRepository with spring data

I know how to install packages in Anaconda using `conda install` and also how to install packages that are on [PyPi][1] which is described in the [manual][2].

But how can I permanently include packages/folders into the `PYTHONPATH` of an Anaconda environment so that code that I am currently working on can be imported and is still available after a reboot?

My current approach is to use `sys`:

    import sys
    sys.path.append(r&#39;/path/to/my/package&#39;)

which is not really convenient.

Any hints?

Thanks in advance!

  [1]: https://pypi.python.org/pypi
  [2]: http://conda.pydata.org/docs/build_tutorials/pkgs.html

Anaconda: Permanently include external packages (like in PYTHONPATH)

Say I have a string: `&quot;Test    me&quot;`.

how do I convert it to: `&quot;Test me&quot;`?

I&#39;ve tried using:

    string?.replace(&quot;\\s+&quot;, &quot; &quot;)

but it appears that `\\s` is an illegal escape in Kotlin.


How do I replace duplicate whitespaces in a String in Kotlin?

Say I have a string: <code>"Test me"</code>.
how do I convert it to: <code>"Test me"</code>?
I've tried using:
<pre><code class="hljs language-c">string?.replace("\\s+", " ")
</code></pre>
but it appears that <code>\\s</code> is an illegal escape in Kotlin.

Should I use double `=`, or triple `=`?


    if(a === null)  {
    //do something
    }


or 


    if(a == null)  {
    //do something
    }



Similarly for &#39;not equals&#39;:


    if(a !== null)  {
    //do something
    }


or 


    if(a != null)  {
    //do something
    }




Best way to null check in Kotlin?

Let&#39;s say I have a list of People which I need to sort by Age first and then by Name. 

Coming from a C#-background, I can easily achieve this in said language by using LINQ:

&lt;!-- language: c# --&gt;

    var list=new List&lt;Person&gt;();
    list.Add(new Person(25, &quot;Tom&quot;));
    list.Add(new Person(25, &quot;Dave&quot;));
    list.Add(new Person(20, &quot;Kate&quot;));
    list.Add(new Person(20, &quot;Alice&quot;));

    //will produce: Alice, Kate, Dave, Tom
    var sortedList=list.OrderBy(person =&gt; person.Age).ThenBy(person =&gt; person.Name).ToList(); 

How does one accomplish this using Kotlin?

This is what I tried (it&#39;s obviously wrong since the output of the first &quot;sortedBy&quot; clause gets overridden by the second one which results in a list sorted by Name only)

&lt;!-- language: java --&gt;

    val sortedList = ArrayList(list.sortedBy { it.age }.sortedBy { it.name })) //wrong

Sort collection by multiple fields in Kotlin

What is the equivalent of a [static initialisation block](https://docs.oracle.com/javase/tutorial/java/javaOO/initial.html) in Kotlin?

I understand that Kotlin is designed to not have static things. I am looking for something with equivalent semantics - code is run once when the class is first loaded.

My specific use case is that I want to enable the DayNight feature from Android AppCompat library and [the instructions](https://medium.com/@chrisbanes/appcompat-v23-2-daynight-d10f90c83e94#.4yv9vdlav) say to put some code in static initialisation block of `Application` class.

Static initialisation block in Kotlin

I have a question, but I&#39;m sitting here in front of my app since hours but I can&#39;t understand what the problem is.

I have an android app (written in kotlin) and I want to make two product flavors and override a class / file in the product flavor:

So my gradle script is that:

    apply plugin: &#39;com.android.application&#39;
    apply plugin: &#39;kotlin-android&#39;
    
    
    android {
      ...
      productFlavors {
        foo {
          applicationId &quot;com.foo&quot;
        }
      }
    }


My files are structured as follows:

     - src
        - androidTest
        - foo
          - java
            - com
              - example
                - Bar.kt
        - main
          - java
            - com
              - example
                - Bar.kt
        - test

So basically I would like to override `Bar.kt` file in `foo` product flavor, but somehow it doesn&#39;t work: It says class Bar is duplicated. 

Any hint?

Product Flavor: Duplicate class found

The code below is creating a new map called `nameTable`, then adding an entry named example to it, then trying to print the name property of the Value.

When I run it, it seems that the plus operation didn&#39;t add a new entry to the map like I thought it would.

So what am I doing wrong? 

    class Person(name1: String, lastName1: String, age1: Int){
        var name: String = name1
        var lastName: String = lastName1
        var age: Int = age1
    }

    var nameTable: MutableMap&lt;String, Person&gt; = mutableMapOf()
    var example = Person(&quot;Josh&quot;, &quot;Cohen&quot;, 24)

    fun main (args: Array&lt;String&gt;){
        nameTable.plus(Pair(&quot;person1&quot;, example))
        for(entry in nameTable){
            println(entry.value.age)
        }
    }

While we&#39;re at it, I would love some examples of how to add, remove, and get an entry from a map.

Content Type	Original Author	Original Content on Stackoverflow
Question	Dina Kleper	View Question on Stackoverflow
Solution 1 - Kotlin	hotkey	View Answer on Stackoverflow

How do I replace duplicate whitespaces in a String in Kotlin?

Kotlin Problem Overview

Kotlin Solutions

Solution 1 - Kotlin

Anaconda: Permanently include external packages (like in PYTHONPATH)

how to show query while using query annotations with MongoRepository with spring data

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