There are a few ways to create an empty list in Dart. If you want a growable list then use an empty list literal like this:

```
[]
```

Or this if you need to specify the type:

```
&lt;String&gt;[]
```

Or this if you want a non-growable (fixed-length) list:

```
List.empty()
```

### Notes

- In the past you could use `List()` but this is now deprecated. The reason is that `List()` did not initialize any members, and that isn&#39;t compatible with null safe code. Read [Understanding null safety: No unnamed List constructor][1] for more.
- [Effective Dart Usage Guide][2]


  [1]: https://dart.dev/null-safety/understanding-null-safety#no-unnamed-list-constructor
  [2]: https://www.dartlang.org/guides/language/effective-dart/usage#do-use-collection-literals-when-possible

Fixed Length List   

     var fixedLengthList = List&lt;int&gt;.filled(5, 0);
     fixedLengthList[0] = 87;

Growable List   

    var growableList = [];
    growableList.add(499);
For more refer [Docs][1]


  [1]: https://api.flutter.dev/flutter/dart-core/List-class.html

&lt;!-- language: cxx --&gt;

    template &lt;typename CRTP&gt;
    struct Pre {
        CRTP &amp; operator++();
    };

    template &lt;typename CRTP&gt;
    struct Post {
        CRTP operator++(int);
    };

    struct Derived
        : Pre&lt;Derived&gt;
        , Post&lt;Derived&gt;
    {};

    int main() {
        Derived d;
        d++;
        ++d;
    }
    
I get these errors from GCC:

&lt;!-- language: none --&gt;

    &lt;source&gt;: In function &#39;int main()&#39;:
    &lt;source&gt;:18:10: error: request for member &#39;operator++&#39; is ambiguous
            d++;
            ^~
    &lt;source&gt;:8:14: note: candidates are: CRTP Post&lt;CRTP&gt;::operator++(int) [with CRTP = Derived]
            CRTP operator++(int);
                ^~~~~~~~
    &lt;source&gt;:3:16: note:                 CRTP&amp; Pre&lt;CRTP&gt;::operator++() [with CRTP = Derived]
            CRTP &amp; operator++();
                    ^~~~~~~~
    &lt;source&gt;:19:11: error: request for member &#39;operator++&#39; is ambiguous
            ++d;
            ^
    &lt;source&gt;:8:14: note: candidates are: CRTP Post&lt;CRTP&gt;::operator++(int) [with CRTP = Derived]
            CRTP operator++(int);
                ^~~~~~~~
    &lt;source&gt;:3:16: note:                 CRTP&amp; Pre&lt;CRTP&gt;::operator++() [with CRTP = Derived]
            CRTP &amp; operator++();
                    ^~~~~~~~

Pre-decrement and post-decrement operators cause similar errors. No such errors with Clang. Any ideas what could be wrong or how to work around this?

GCC can&#39;t differentiate between operator++() and operator++(int)

All I need is my text to be multi-line. Am giving the property of `maxLines` but its still getting `RenderFlex` overflowed error to the right as the next is not going to 2nd line,


          Align( alignment: Alignment.bottomCenter,
          child: new ButtonBar(
            alignment: MainAxisAlignment.center,
            children: &lt;Widget&gt;[
              Padding(
                padding: EdgeInsets.all(20.0),
                child: new Text(
                  &quot;This is a very bigggggggg text !!!&quot;,textDirection: TextDirection.ltr,
                  style: new TextStyle(fontSize: 20.0, color: Colors.white),
                  maxLines: 2,
                ),
              )
            ],
          ),
        )



Flutter Multiline for text

I want to create an empty list for a Flutter project.

    final prefs = await SharedPreferences.getInstance();
    final myStringList = prefs.getStringList(&#39;my_string_list_key&#39;) ?? &lt;empty list&gt;;

I seem to remember there are multiple ways but one recommended way. How do I do it?

How to create an empty list in Dart

I want to create an empty list for a Flutter project.
<pre><code class="hljs language-ini">final prefs = await SharedPreferences.getInstance();
final myStringList = prefs.getStringList('my_string_list_key') ?? &#x3C;empty list>;
</code></pre>
I seem to remember there are multiple ways but one recommended way. How do I do it?

I am trying to get the JSON response from the server and output it to the console.

    Future&lt;String&gt; login() async {
        var response = await http.get(
            Uri.encodeFull(&quot;https://etrans.herokuapp.com/test/2&quot;),
            headers: {&quot;Accept&quot;: &quot;application/json&quot;});
    
        this.setState(() {
          data = json.decode(response.body);
        });
    
    
        print(data[0].name);
        return &quot;Success!&quot;;
      }

&gt; Unhandled Exception: type &#39;_InternalLinkedHashMap&lt;String, dynamic&gt;&#39; is
&gt; not a subtype of type &#39;List&lt;dynamic&gt;

What could be the reason?


Unhandled Exception: InternalLinkedHashMap&lt;String, dynamic&gt;&#39; is not a subtype of type &#39;List&lt;dynamic&gt;

I&#39;m trying to add an element list to the list of string, but I found `Kotlin` does not have an add function like `java` so please help me out how to add the items to the list. 

	class RetrofitKotlin : AppCompatActivity() {

		var listofVechile:List&lt;Message&gt;?=null
		var listofVechileName:List&lt;String&gt;?=null
		var listview:ListView?=null
		var progressBar:ProgressBar?=null
		override fun onCreate(savedInstanceState: Bundle?) {
			super.onCreate(savedInstanceState)
			setContentView(R.layout.activity_retrofit_kotlin)

			listview=findViewById&lt;ListView&gt;(R.id.mlist)
			var apiInterfacee=ApiClass.client.create(ApiInterfacee::class.java)
			val call=apiInterfacee.getTaxiType()
			call.enqueue(object : Callback&lt;TaxiTypeResponse&gt; {

				override fun onResponse(call: Call&lt;TaxiTypeResponse&gt;, response: Response&lt;TaxiTypeResponse&gt;) {

					listofVechile=response.body()?.message!!
					println(&quot;Sixze is here listofVechile   ${listofVechile!!.size}&quot;)
					if (listofVechile!=null) {
						for (i in 0..listofVechile!!.size-1) {

							//how to add the name only listofVechileName list

						}
					}
					//println(&quot;Sixze is here ${listofVechileName!!.size}&quot;)
					val arrayadapter=ArrayAdapter&lt;String&gt;(this@RetrofitKotlin,android.R.layout.simple_expandable_list_item_1,listofVechileName)
					listview!!.adapter=arrayadapter

				}
				override fun onFailure(call: Call&lt;TaxiTypeResponse&gt;, t: Throwable) {
				 
				}
			})
		}
	}

How to add an item to a list in Kotlin?

```python
list = [&quot;a&quot;, &quot;b&quot;, &quot;c&quot;, &quot;d&quot;]
print(list[3]) # Number 3 is &quot;d&quot;

print(list[-4]) # Number -4 is &quot;a&quot;
```

Why does Python start at index -1 (as opposed to 0) when indexing a list from the end?

Consider, for example,

    squares = *map((2).__rpow__, range(5)),
    squares
    # (0, 1, 4, 9, 16)
     
    *squares, = map((2).__rpow__, range(5))
    squares
    # [0, 1, 4, 9, 16]

So, all else being equal we get a list when splatting on the lhs and a tuple when splatting on the rhs.

Why?

Is this by design, and if yes, what&#39;s the rationale? Or, if not, are there any technical reasons? Or is this just how it is, no particular reason?


Why does splatting create a tuple on the rhs but a list on the lhs?

I am reading through the &quot;Starting Out&quot; chapter of [*Learn You a Haskell for Great Good!*](http://learnyouahaskell.com/starting-out). It says:

&gt; `null` checks if a list is empty. If it is, it returns **`True`**, otherwise it returns **`False`**. Use this function instead of **`xs == []`** (if you have a list called **`xs`**)

I tried in ghci:
```
xs = []      -- and then,

xs == []
null xs
```
Both of them are `True`.

I wonder what&#39;s the difference. 

Should I use the `null` function instead of `== []` and why?

Why use null function instead of == [] to check for empty list in Haskell?

The following line of code has two question marks:

    final myStringList = prefs.getStringList(&#39;my_string_list_key&#39;) ?? [];

What is the meaning?

What are the ?? double question marks in Dart?

Is there a built in widget in Flutter to create a divider with text in the middle? Any guide on how to do it? Like this: (the &quot;OR&quot; text in the middle of horizontal line)

[here&#39;s is the screenshot of what I want to achieve][1]


  [1]: https://i.stack.imgur.com/VyJXx.png

Horizontal divider with text in the middle in Flutter?

What&#39;s the best programming practice to 

&gt; create a constant class in Flutter

 to keep all the application constants for easy reference. I know that there is `const` keyword in Dart for creating constant fields, but is it okay to use `static` along with const, or will it create memory issues during run-time.
 
    class Constants {
    static const String SUCCESS_MESSAGE=&quot; You will be contacted by us very soon.&quot;;
    }

What&#39;s the best practice to keep all the constants in Flutter?

I have an error when I tried to launch my project on my iPhone, the basic Flutter example is working on my iPhone but when I use my project I have this error. 

[![enter image description here][1]][1]


  [1]: https://i.stack.imgur.com/Ri042.jpg

How to solve &quot;error running pod install&quot; in flutter on mac?

I was trying to build a border for my text field like:

    return TextField(
      ...
     border: OutlineInputBorder(
      borderSide: BorderSide(
       color: Colors.red, 
        width: 5.0),
        )
      )
    )

But it always return a black border with 1.0 as width. 
The only way that I found to change the color was to create a ThemeData where I specify the hint color, but I could not find a way to change my width.

Flutter: Outline input border

So like most, i&#39;m new to Bloc and flutter and dart and wrapping my head around. I&#39;ve googled, looked through the posts here but haven&#39;t found really any answers.

So this is about navigation with bloc and flutter. Take the example of a Login. So there is a login page with a bloc behind it and at some point someone presses a button to login.

So we can call a function in the bloc that does the validation. I think this is against the strict approach but i see people doing this. But then if login is successful how do you navigate to the next screen? You&#39;re not supposed to navigate in a bloc?

But if that login page is using a StreamBuilder to change state then you cannot add a navigate in a builder either can you? You can&#39;t return navigation, you return widgets.

The initstate is somewhere you could navigate, but can you have a stream builder in an initstate that listens for state changes in the bloc?

It&#39;s all a little confusing right now but i&#39;m persevering as this is *supposed* to be the way forward...

thanks
Paul

Content Type	Original Author	Original Content on Stackoverflow
Question	Suragch	View Question on Stackoverflow
Solution 1 - List	Suragch	View Answer on Stackoverflow
Solution 2 - List	Abdulhakim Zeinu	View Answer on Stackoverflow

How to create an empty list in Dart

List Problem Overview

List Solutions

Solution 1 - List

Notes

Solution 2 - List

Flutter Multiline for text

GCC can't differentiate between operator++() and operator++(int)

Attributions