You can use plus:

    assert [ a: true, b: false ] + [ a: false ] == [ a: false, b: false ]

Or left shift:

    assert [ a: true, b: false ] &lt;&lt; [ a: false ] == [ a: false, b: false ] 

The difference is that `&lt;&lt;` [adds the right hand map into the left hand map][1].  When you use `+`, it [constructs a new Map based on the LHS][2], and adds the right hand map into it


  [1]: https://github.com/groovy/groovy-core/blob/GROOVY_2_4_X/src/main/org/codehaus/groovy/runtime/DefaultGroovyMethods.java#L12296
  [2]: https://github.com/groovy/groovy-core/blob/GROOVY_2_4_X/src/main/org/codehaus/groovy/runtime/DefaultGroovyMethods.java#L7433

I am new on Oracle database, but I have one issue. 
On my Database server (server1) listener and database instance run correctly and I can use `sqlplus` to connect to this DB.
When I connect to database by using other server, I check the TNS configuration and it is correct but system says:                                    

&gt;     ERROR:
&gt;     ORA-12541: TNS:no listener

My database is Oracle 10gR2

So how can I solve this issue?

Oracle client ORA-12541: TNS:no listener

I&#39;ve run into a curious issue - apparently some Node.js module have so ***deep* folder hierarchies** that Windows copy command (or PowerShell&#39;s `Copy-Item` which is what we&#39;re actually using) hits the infamous &quot;path too long&quot; error when path is over 250 chars long.

For example, this is a folder hierarchy that a single Node module can create:

    node_modules\nodemailer\node_modules\simplesmtp\node_modules\
    xoauth2\node_modules\request\node_modules\form-data\node_modules\
    combined-stream\node_modules\delayed-stream\...

It seems insane but is a reality with Node modules.

We need to use copy-paste during deployment (we&#39;re not using a &quot;clever&quot; target platform like Heroku where Git deployment would be an option) and this is a serious limitation on Windows.

**Isn&#39;t there a npm command or something that would compact the `node_modules` folder or maybe include only what&#39;s actually necessary at runtime?** (Node modules usually contain `test` folders etc. which we don&#39;t need to deploy.) Any other ideas how to work around it? Not using Windows is unfortunately not an option :)

How to deploy Node.js application with deep node_modules structure on Windows?

First map is default options `[a: true, b: false]`. Second map - options passed by user `[a:false]`. Does Groovy has maps merge method to obtain `[a: false, b:false]`?   

It&#39;s not problem to implement it in Groovy. I&#39;m asking about method out of the box

Does Groovy have method to merge 2 maps?

<p>First map is default options <code>[a: true, b: false]</code>. Second map - options passed by user <code>[a:false]</code>. Does Groovy has maps merge method to obtain <code>[a: false, b:false]</code>?</p>
<p>It's not problem to implement it in Groovy. I'm asking about method out of the box</p>


If I have a map `m` is there a better way of getting a slice of the values `v` than this?


    package main
    import (
      &quot;fmt&quot;
    )

    func main() {
        m := make(map[int]string)

        m[1] = &quot;a&quot;
        m[2] = &quot;b&quot;
        m[3] = &quot;c&quot;
        m[4] = &quot;d&quot;

        // Can this be done better?
        v := make([]string, len(m), len(m))
        idx := 0
        for  _, value := range m {
           v[idx] = value
           idx++
        }

        fmt.Println(v)
     }

Is there a built-in feature of a `map`? Is there a function in a Go package, or is this the only way to do this?

In Go how to get a slice of values from a map?

I am trying to implement a dictionary (as in the physical book). I have a list of words and their meanings. 

What data structure / type does Java provide to store a list of words and their meanings as key/value pairs. 

How, given a key, can I find and return the value?


How do you create a dictionary in Java?

I have some JavaScript code that uses objects as dictionaries; for example a &#39;person&#39; object will hold a some personal details keyed off the email address.
    
    var people = {&lt;email&gt; : &lt;&#39;some personal data&#39;&gt;};

    adding   &gt; &quot;people[&lt;email&gt;] = &lt;data&gt;;&quot; 
    getting  &gt; &quot;var data = people[&lt;email&gt;];&quot; 
    deleting &gt; &quot;delete people[&lt;email&gt;];&quot;

Is it possible to describe this in Typescript? or do I have to use an Array?



TypeScript Objects as Dictionary types as in C#

I&#39;m trying to take a file that looks like this:
```none
AAA x 111
AAB x 111
AAA x 112
AAC x 123
...
```
And use a dictionary to so that the output looks like this

    {AAA: [&#39;111&#39;, &#39;112&#39;], AAB: [&#39;111&#39;], AAC: [123], ...}

This is what I&#39;ve tried

    file = open(&quot;filename.txt&quot;, &quot;r&quot;) 
    readline = file.readline().rstrip()
    while readline!= &quot;&quot;:
        list = []
        list = readline.split(&quot; &quot;)
        j = list.index(&quot;x&quot;)
        k = list[0:j]
        v = list[j + 1:]
        d = {}
        if k not in d == False:
            d[k] = []
        d[k].append(v)
        readline = file.readline().rstrip()

I keep getting a `TypeError: unhashable type: &#39;list&#39;`. I know that keys in a dictionary can&#39;t be lists but I&#39;m trying to make my value into a list not the key. I&#39;m wondering if I made a mistake somewhere.


How to overcome TypeError: unhashable type: &#39;list&#39;

Suppose I wanted to map data with a string as the key.
What container should I have chosen, `map` or `unordered_map`? `unordered_map` takes up more memory so let&#39;s suppose memory isn&#39;t an issue, and the concern is speed.

`unordered_map` should generally give average complexity of O(1) with the worst case of O(n).
In what cases would it get to O(n)?
When does a `map` get more time efficient than `unordered_map`? Does it happen when n is small?

Assuming I would use STL `unordered_map` with the default haser Vs. map. string is the key.

If I&#39;m going to iterate over the elements rather than access an individual element each time, should I prefer `map`?

How to choose between map and unordered_map?

I have method

    def test(String a, String b) { }

and I would like to call this with a dynamic parameter map.
I always though that

    test([&#39;1&#39;,&#39;2&#39;]); //valid call

and also 
 
    test([a:&#39;1&#39;,b:&#39;2&#39;]); //=&gt; does not work

will work. but it doesn&#39;t. So I remembered [the spread operator][1], but can&#39;t get it to work....

Is there a way to call a method like the one above with some kind of map as parameter instead of single parameters?


  [1]: https://groovy-lang.org/operators.html#_spread_operator

Named parameters

I want to find a specific key in a given map. If the key is found, I then want to get the value of that key from the map.

This is what I managed so far:

    def mymap = [name:&quot;Gromit&quot;, likes:&quot;cheese&quot;, id:1234]
    
    def x = mymap.find{ it.key == &quot;likes&quot; }

    if(x)
        println x.value


This works, the output is &quot;cheese&quot; as expected. Great, but I don&#39;t want to do `x.value` at the end, and I don&#39;t want to do `if(x)`. I want x to directly contain the value somehow.

I can&#39;t get the value directly into x like this:

    def mymap = [name:&quot;Gromit&quot;, likes:&quot;cheese&quot;, id:1234]
    
    def x = mymap.find{ it.key == &quot;likesZZZ&quot; }.value
    
    println x

Because the find closure is null in this case, this results in a Null Pointer Exception. Of course, the above code snippet works when `it.key == &quot;likes&quot;`, but I am not sure that I will always find the target key in the map.

What is a &quot;Groovier&quot; and safe way to do this on a map:

- Check if a map has a given key,
- And if so, get the value of this key

groovy: safely find a key in a map and return its value

I&#39;m new to Java/Groovy development and I have a simple string that I would like to reformat, however I get an &#39;Unparseable date&#39; error when I attempt to run the following:

    import java.text.SimpleDateFormat 
    import java.util.Date

    String oldDate
    Date date
    String newDate 

    oldDate = &#39;04-DEC-2012&#39;
    date = new SimpleDateFormat(&quot;yyyy-MM-dd HH:mm:ss.S&quot;).parse(oldDate)
    newDate = new SimpleDateFormat(&quot;M-d-yyyy&quot;).format(date) 

    println newDate

I&#39;m sure it&#39;s something simple, but the solution eludes me.  Can anyone help?

Java/Groovy - simple date reformatting

I&#39;m new to gradle and am currently just trying to follow the tutorials and quite a few times I&#39;ve seen single and double quotes intermixed. I just wanted to know if there was a difference of when one set should be used over the other. One example of this is section 6.12 of the tutorial - [Default tasks][1]:

    defaultTasks &#39;clean&#39;, &#39;run&#39;

    task clean &lt;&lt; {
        println &#39;Default Cleaning!&#39;
    }

    task run &lt;&lt; {
        println &#39;Default Running!&#39;
    }

    task other &lt;&lt; {
        println &quot;I&#39;m not a default task!&quot;
    }

So, I would just like to know if I should be paying attention to these differences or if they are inter-changable and I can use either single or double quotes when printing strings in gradle.

  [1]: http://www.gradle.org/docs/current/userguide/tutorial_using_tasks.html

Gradle Single vs Double Quotes

I tried to open the Groovy Shell (`groovysh`) on Windows 8 and got the following output:

    java.util.prefs.WindowsPreferences &lt;init&gt;
    WARNING: Could not open/create prefs root node Software\JavaSoft\Prefs 
    at root 0x80000002. Windows RegCreateKeyEx(...) returned error code 5.

After printing the above message the shell started as expected.



Content Type	Original Author	Original Content on Stackoverflow
Question	fedor.belov	View Question on Stackoverflow
Solution 1 - Dictionary	tim_yates	View Answer on Stackoverflow

Does Groovy have method to merge 2 maps?

Dictionary Problem Overview

Dictionary Solutions

Solution 1 - Dictionary

How to deploy Node.js application with deep node_modules structure on Windows?

Oracle client ORA-12541: TNS:no listener

Attributions