**Differences:**

1. They both provide many common features like `onTap`, `onLongPress` etc. The main difference is `GestureDetector` provides more controls like dragging etc. on the other hand it doesn&#39;t include ripple effect tap, which `InkWell` does. 


2. You can use either of them according to your needs, you want ripple effects go with `InkWell`, need more controls go with `GestureDetector` or even combine both of them.  

---

**Ripple effect (using `InkWell`):**

```dart
InkWell(
  onTap: () {},
  child: Ink(
    width: 200,
    height: 200,
    color: Colors.blue,
  ),
)
```

[![enter image description here][1]][1]


  [1]: https://i.stack.imgur.com/rYcq2.gif

I will try to mention the functionality difference they have.

`GestureDetector` class is very broad. you can detect every type of interaction the user has with the screen or widget using it. it includes pinch, swipe, touch, plus custom gestures.

`InkWell` has a limited number of gestures to detect but it gives you ways to decorate the widget. you can decorate 

colors:` splashColor`, `focusColor`, `hoverColor`...

border: `borderRadius`,`customBorder`, ...

hope this is helpful!

**Visual Difference** &lt;br&gt;
&lt;img src=&quot;https://i.stack.imgur.com/XfEpx.gif&quot; width=&quot;400&quot;&gt;
------------------------------------------------------------------------

Other answers are absolutely right. This is the visual representation.

For me the important difference between them is: **InkWell must have a Material widget as an ancestor**, while GestureDetector does not need a Material widget as ancestor.

The InkWell makes the whole area of the child as hotspot and receives user interaction easily. However, the GestureDetector does not make the whole area of the child as hotspot, like the padding areas aren&#39;t hotspots. Thus, using GestureDetector often leads to failed user interaction.

I know about two ways to exclude elements of a computation from the gradient calculation `backward`

**Method 1:** using `with torch.no_grad()`
```
with torch.no_grad():
    y = reward + gamma * torch.max(net.forward(x))
loss = criterion(net.forward(torch.from_numpy(o)), y)
loss.backward();
```
**Method 2:** using `.detach()`
```
y = reward + gamma * torch.max(net.forward(x))
loss = criterion(net.forward(torch.from_numpy(o)), y.detach())
loss.backward();
```


Is there a difference between these two? Are there benefits/downsides to either?

Difference between &quot;detach()&quot; and &quot;with torch.nograd()&quot; in PyTorch?

I&#39;m trying to build a simple watchOS UI with SwiftUI with two pieces of information side-by-side above a button.

I&#39;d like each side (represented as a `VStack` within an `HStack`) to take up half of the available width (so it&#39;s an even 50/50 split within the yellow parent view) divided where the *|* character is centered on the button in the example below.

I want the *Short* and *Longer!!!* text to each be centered within each side&#39;s 50%.

I started with this code, to get the elements in place and show the bounds of some of the different stacks:

    var body: some View {
        VStack {
            HStack {
                
                VStack {
                    Text(&quot;Short&quot;).font(.body)
                }
                    .background(Color.green)
                
                VStack {
                    Text(&quot;Longer!!!&quot;).font(.body)
                }
                    .background(Color.blue)

            }
                .frame(minWidth: 0, maxWidth: .infinity)
                .background(Color.yellow)
            Button (action: doSomething) {
                Text(&quot;|&quot;)
            }
        }
    }

Which gave me this result:
[![starting point][1]][1]

Then, when it comes to making each side-by-side `VStack` 50% of the available width, I&#39;m stuck. I thought it should work to add `.relativeWidth(0.5)` to each `VStack`, which should, as I understand it, make each `VStack` half the width of its parent view (the `HStack`, with the yellow background):

    var body: some View {
        VStack {
            HStack {
                
                VStack {
                    Text(&quot;Short&quot;).font(.body)
                }
                    .relativeWidth(0.5)
                    .background(Color.green)
                
                VStack {
                    Text(&quot;Longer!!!&quot;).font(.body)
                }
                    .relativeWidth(0.5)
                    .background(Color.blue)

            }
                .frame(minWidth: 0, maxWidth: .infinity)
                .background(Color.yellow)
            Button (action: doSomething) {
                Text(&quot;|&quot;)
            }
        }
    }

But this is the result I get:
[![unexpected widths][2]][2]

How can I get the behavior I want with SwiftUI?


----------


**Update:** After reviewing the SwiftUI documentation more, I see [the example here][3] that sets a frame and then defines a relative width in comparison to that frame, so maybe I&#39;m not supposed to use `relativeWidth` in this way?

I&#39;m a step closer to what I want with the following code:

    var body: some View {
        VStack {
            HStack {
                
                VStack {
                    Text(&quot;Short&quot;).font(.body)
                }
                    .frame(minWidth: 0, maxWidth: .infinity)
                    .background(Color.green)
                
                VStack {
                    Text(&quot;Longer!!!&quot;).font(.body)
                }
                    .frame(minWidth: 0, maxWidth: .infinity)
                    .background(Color.blue)

            }
                .frame(minWidth: 0, maxWidth: .infinity)
                .background(Color.yellow)
            Button (action: doSomething) {
                Text(&quot;|&quot;)
            }
        }
    }

which produces this result:

[![closer to expected result][4]][4]

Now, I am trying to figure out what&#39;s creating that extra space in the middle between the two `VStack`s. So far, experimenting with getting rid of padding and ignoring safe areas does not seem to affect it.


  [1]: https://i.stack.imgur.com/nSl4i.png
  [2]: https://i.stack.imgur.com/6rz77.png
  [3]: https://developer.apple.com/documentation/swiftui/securefield/3289408-relativewidth
  [4]: https://i.stack.imgur.com/CLx40.png

Equal widths of subviews with SwiftUI

I&#39;m completely new to Flutter and found out about `InkWell` and `GestureDetector`. It seemed to me that they are almost the same. The official documentation doesn&#39;t provide any in-depth comparison between them. 

 1. What are the differences between `InkWell` and `GestureDetector`?
    
 2. When to use which?

Flutter: InkWell vs GestureDetector: what is the difference?

I'm completely new to Flutter and found out about <code>InkWell</code> and <code>GestureDetector</code>. It seemed to me that they are almost the same. The official documentation doesn't provide any in-depth comparison between them.
<ol>
<li>
What are the differences between <code>InkWell</code> and <code>GestureDetector</code>?
</li>
<li>
When to use which?
</li>
</ol>

I want to show an icon in text widget. How do I do this ? 

The following code only shows the ```IconData```

```
Text(&quot;Click ${Icons.add} to add&quot;);
```

How to show Icon in Text widget in flutter?

I want to add `,00` at the end of the value of the textfield. 

It works well in iOS device, but in android cursor moves to starting point of the value in textfield. As a result, I&#39;m unable to add `,00`.

how to set cursor position at the end of the value in flutter in textfield?

I followed the steps in the Flutter document and tried to build my first Flutter app in Intellij IDEA. And when I try to run it,there was an error about my JAVA_HOME variable. And an error about cannot resolve symbol &quot;Properties&quot; in the build.gradle file. I really don&#39;t know what to do.

This is my error information displayed in the Console window.

    Launching lib\main.dart on Android SDK built for x86 in debug mode...
    Initializing gradle...
    Finished with error: ProcessException: Process 
    &quot;F:\untitled\android\gradlew.bat&quot; exited abnormally:

    ERROR: JAVA_HOME is set to an invalid directory: F:\Google download\jdk- 
    10.0.1_windows-x64_bin.exe

    Please set the JAVA_HOME variable in your environment to match the
    location of your Java installation.
      Command: F:\untitled\android\gradlew.bat -v

Actually there is nothing wrong with my JAVA_HOME variable, I set it to the proper directory: C:\Program Files (x86)\Java\jdk1.8.0_131.

And I run the command it shows above &quot;F:\untitled\android\gradlew.bat -v&quot;, it seemed to update the gradle version, but the error didn&#39;t resolved.

And this is the code in build.gradle file.

```
def localProperties = new Properties() 
//there will be a highlight on Properties indicates that &#39;cannot resolve symbol &quot;Properties&quot; &#39;

def localPropertiesFile = rootProject.file(&#39;local.properties&#39;)
if (localPropertiesFile.exists()) {
    localPropertiesFile.withReader(&#39;UTF-8&#39;) { reader -&gt;
        localProperties.load(reader)
    }
}

def flutterRoot = localProperties.getProperty(&#39;flutter.sdk&#39;)
if (flutterRoot == null) {
    throw new GradleException(&quot;Flutter SDK not found. Define location with flutter.sdk in the local.properties file.&quot;)
//the same as the Properties on GradleException
}

def flutterVersionCode = localProperties.getProperty(&#39;flutter.versionCode&#39;)
if (flutterVersionCode == null) {
    flutterVersionCode = &#39;1&#39;
}

def flutterVersionName = localProperties.getProperty(&#39;flutter.versionName&#39;)
if (flutterVersionName == null) {
    flutterVersionName = &#39;1.0&#39;
}

apply plugin: &#39;com.android.application&#39;
apply from: &quot;$flutterRoot/packages/flutter_tools/gradle/flutter.gradle&quot;

android {
    compileSdkVersion 28

    lintOptions {
        disable &#39;InvalidPackage&#39;
    }

    defaultConfig {
        // TODO: Specify your own unique Application ID (https://developer.android.com/studio/build/application-id.html).
        applicationId &quot;com.example.untitled&quot;
        minSdkVersion 16
        targetSdkVersion 28
        versionCode flutterVersionCode.toInteger()
        versionName flutterVersionName
        testInstrumentationRunner &quot;android.support.test.runner.AndroidJUnitRunner&quot;
    }

    buildTypes {
        release {
            // TODO: Add your own signing config for the release build.
            // Signing with the debug keys for now, so `flutter run --release` works.
            signingConfig signingConfigs.debug
        }
    }
}

flutter {
    source &#39;../..&#39;
}

dependencies {
    testImplementation &#39;junit:junit:4.12&#39;
    androidTestImplementation &#39;com.android.support.test:runner:1.0.2&#39;
    androidTestImplementation &#39;com.android.support.test.espresso:espresso-core:3.0.2&#39;
}
```

First Flutter App error: cannot resolve symbol &quot;Properties&quot;

I have code like this but I want it to iterate over an integer array to display a dynamic amount of children:

    return Container(
      child: Column(
        children: &lt;Widget&gt;[
          Center(
            child: Text(text[0].toString(),
                textAlign: TextAlign.center),
          ),
          Center(
            child: Text(text[1].toString(),
                textAlign: TextAlign.center),
          ),
        ],
      ),
    )

Where the `text` variable is a list of integers converter to string here. I tried adding a function to iterate through the array and display the &#39;children&#39; but was getting a type error. Not sure how to do it since I&#39;m new to Dart and Flutter.

Flutter for loop to generate list of widgets

In my flutter project, I have initialized a Row. Inside that, I created some Texts in a column and after that, I want to add a line but it is not showing anything. I have used Expanded for that reason and followed the given solutions-

[https://stackoverflow.com/questions/54058228/horizontal-divider-with-text-in-the-middle-in-flutter][1]

But none of them worked either.

Here&#39;s the image of my code output-

[![enter image description here][2]][2]

Here&#39;s my code-

    Container(
          color:Colors.white,
          child: (
            Row(
              children: &lt;Widget&gt;[
                Padding(
                  padding: const EdgeInsets.all(8.0),
                  child: Image(
                      height: 100,
                      width: 100,
                      image: NetworkImage(&quot;https://www.gstatic.com/webp/gallery/1.jpg&quot;),
                    ),
                ),
                Column(
                  children: &lt;Widget&gt;[
                    Text(&quot;Book Name&quot;),
                    Text(&quot;Author name&quot;),

                    Divider(
                      color: Colors.black,
                    )
                  ],
                )
              ],
            )
          ),
        ),


So, I need a line below the two texts and show it like the below picture-

[![enter image description here][3]][3]


  [1]: https://stackoverflow.com/questions/54058228/horizontal-divider-with-text-in-the-middle-in-flutter
  [2]: https://i.stack.imgur.com/4sNQT.png
  [3]: https://i.stack.imgur.com/e4T13.png

How to draw a horizontal line in flutter row widgets?

I want to open `Drawer` programmatically not by sliding  it, how to disable that sliding functionality (touch functionality of Drawer)

Flutter: How to open Drawer programmatically

I want to have a `ListView` inside another widget when I wrap `FutureBuilder` in a `Column` in order to have a simple `Row`. I get this error:

```
The following assertion was thrown during performLayout():
I/flutter (13816): RenderFlex children have non-zero flex but incoming height constraints are unbounded.
I/flutter (13816): When a column is in a parent that does not provide a finite height constraint, for example, if it is
I/flutter (13816): in a vertical scrollable, it will try to shrink-wrap its children along the vertical axis. Setting a
I/flutter (13816): flex on a child (e.g. using Expanded) indicates that the child is to expand to fill the remaining
I/flutter (13816): space in the vertical direction.
I/flutter (13816): These two directives are mutually exclusive. If a parent is to shrink-wrap its child, the child
I/flutter (13816): cannot simultaneously expand to fit its parent.
I/flutter (13816): Consider setting mainAxisSize to MainAxisSize.min and using FlexFit.loose fits for the flexible
I/flutter (13816): children (using Flexible rather than Expanded). This will allow the flexible children to size
I/flutter (13816): themselves to less than the infinite remaining space they would otherwise be forced to take, and
I/flutter (13816): then will cause the RenderFlex to shrink-wrap the children rather than expanding to fit the maximum
I/flutter (13816): constraints provided by the parent.
I/flutter (13816): If this message did not help you determine the problem, consider using debugDumpRenderTree():
```

My code:

```dart
class ActivityShowTicketReplies extends StatefulWidget {
  final Map&lt;String, dynamic&gt; ticketData;

  ActivityShowTicketReplies({@required this.ticketData});

  @override
  State&lt;StatefulWidget&gt; createState() =&gt; ActivityShowTicketRepliesState();
}

class ActivityShowTicketRepliesState extends State&lt;ActivityShowTicketReplies&gt; {
  TicketsTableData get _ticket =&gt; TicketsTableData.fromJson(json.decode(widget.ticketData.values.toList()[0][0].toString()));

  @override
  Widget build(BuildContext context) {
    return ScopedModel(
      model: CounterModel(),
      child: Directionality(
        textDirection: TextDirection.rtl,
        child: Scaffold(
          body: Column(
            children: &lt;Widget&gt;[
              Row(
                mainAxisAlignment: MainAxisAlignment.center,
                crossAxisAlignment: CrossAxisAlignment.center,
                children: &lt;Widget&gt;[
                  Padding(
                    padding: const EdgeInsets.symmetric(vertical: 20.0),
                    child: RaisedButton(
                      color: Colors.indigo,
                      onPressed: () =&gt; BlocProvider.of&lt;AppPagesBloc&gt;(context).dispatch(FragmentNavigateEvent(routeName: FRAGMENT_NEW_TICKET)),
                      shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(50.0)),
                      child: Container(
                        child: Text(
                          &#39;new ticket&#39;,
                          style: AppTheme(context).caption().copyWith(color: Colors.white),
                        ),
                      ),
                    ),
                  ),
                ],
              ),
              FutureBuilder(
                future: Provider.of&lt;TicketRepliesTableDao&gt;(context).find(ticketId: _ticket.id),
                builder: (context, snapshot) {
                  if (snapshot.connectionState == ConnectionState.done) {
                    if (snapshot.hasData) {
                      final List&lt;TicketRepliesTableData&gt; ticketReplies = snapshot.data;
                      if (ticketReplies.isNotEmpty) {
                        return Column(
                          children: &lt;Widget&gt;[
                            Card(
                              clipBehavior: Clip.antiAlias,
                              color: Colors.grey[50],
                              margin: EdgeInsets.all(10.0),
                              child: InkWell(
                                child: Stack(
                                  children: &lt;Widget&gt;[
                                    Column(
                                      children: &lt;Widget&gt;[
                                        Padding(
                                          padding: const EdgeInsets.symmetric(vertical: 12.0),
                                          child: ListTile(
                                            title: Padding(
                                              padding: const EdgeInsets.symmetric(vertical: 5.0),
                                              child: Text(
                                                &#39;subject&#39;,
                                                style: AppTheme(context).caption().copyWith(fontFamily: &#39;ShabnamBold&#39;),
                                              ),
                                            ),
                                            subtitle: Text(
                                              _ticket.subject,
                                              style: AppTheme(context).caption(),
                                            ),
                                          ),
                                        ),
                                        Container(
                                          height: 30.0,
                                          margin: EdgeInsets.zero,
                                          width: double.infinity,
                                          color: Colors.grey[200],
                                          child: Row(
                                            mainAxisAlignment: MainAxisAlignment.center,
                                            children: &lt;Widget&gt;[
                                              
                                            ],
                                          ),
                                        ),
                                      ],
                                    ),
                                    Align(
                                      alignment: Alignment.topLeft,
                                      child: Container(
                                          margin: EdgeInsets.only(top: 10.0),
                                          constraints: BoxConstraints(
                                            minWidth: 70.0,
                                          ),
                                          height: 20.0,
                                          width: 70.0,
                                          decoration: BoxDecoration(
                                              color: Colors.green[200],
                                              borderRadius: BorderRadius.only(
                                                topRight: Radius.circular(5.0),
                                                bottomRight: Radius.circular(5.0),
                                              )),
                                          child: Center(
                                            child: Text(
                                              &#39;status&#39;,
                                              style: AppTheme(context).overLine().copyWith(fontFamily: &#39;ShabnamBold&#39;, color: Colors.black),
                                            ),
                                          )),
                                    ),
                                  ],
                                ),
                                onTap: () {},
                              ),
                            ),
                            Expanded(
                              child: ListView.builder(
                                itemBuilder: (context, index) {
                                  return Card(
                                    clipBehavior: Clip.antiAlias,
                                    child: Padding(
                                      padding: const EdgeInsets.all(20.0),
                                      child: Column(
                                        mainAxisAlignment: MainAxisAlignment.start,
                                        crossAxisAlignment: CrossAxisAlignment.start,
                                        children: &lt;Widget&gt;[
                                          Row(
                                            children: &lt;Widget&gt;[
                                              Text(
                                                ticketReplies[index].createdAt,
                                                style: AppTheme(context).caption().copyWith(fontFamily: &#39;ShabnamLight&#39;),
                                              ),
                                            ],
                                          ),
                                          ListTile(
                                            title: Text(ticketReplies[index].reply),
                                          ),
                                        ],
                                      ),
                                    ),
                                  );
                                },
                                itemCount: ticketReplies.length,
                              ),
                            ),
                          ],
                        );
                      } else {
                        return Center(
                          child: Text(
                            &#39;there isn&#39;t any reply message&#39;,
                            style: AppTheme(context).caption(),
                          ),
                        );
                      }
                    } else {
                      return _loader(context, &#39;no reply&#39;);
                    }
                  } else
                    return _loader(context, Strings.pleaseWait);
                },
              ),
            ],
          ),
        ),
      ),
    );
  }

  Widget _loader(BuildContext context,String message) {
    return Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          crossAxisAlignment: CrossAxisAlignment.center,
          children: &lt;Widget&gt;[
            ColorLoader3(
              radius: 25.0,
              dotRadius: 5.0,
            ),
            Padding(
              padding: const EdgeInsets.all(3.0),
              child: Text(
                Strings.pleaseWait,
                style: AppTheme(context).caption().copyWith(color: Colors.red[900]),
              ),
            ),
          ],
        ));
  }
}
```



Flutter: &quot;RenderFlex children have non-zero flex but incoming height constraints are unbounded&quot;

```      
Container(
      child: Text(
          &#39;This is a Container&#39;,
          textScaleFactor: 2,
          style: TextStyle(color: Colors.black),
      ),
                  
      decoration: BoxDecoration(
          borderRadius: BorderRadius.circular(10),
          color: Colors.white,
          border: Border(
              left: BorderSide(
                  color: Colors.green,
                  width: 3,
              ),
            ),
          ),
      height: 50,
     ),
```

This is supposed to show a rounded-edged container with a green left border 3px wide, and the child Text &quot;This is a Container&quot;. However, it just shows a rounded-edged container with an invisible child and an invisible left border.

When I take out the borderRadius object, the child Text and the green left border is visible, but introducing it hides the left border and child Text again. 

The major problem seems to be the custom left border, because using `border: Border.all(width: 0)` and `borderRadius: BorderRadius.circular(10)` makes the edges rounded as needed and also shows the child. But now I cant apply the green left border which is quite important in this particular setup.

So is there something I&#39;m doing wrong, or is this a bug in flutter, or is it just something that is not allowed?

Thank you in advance.

Edit: The image below is the end result. The colors don&#39;t matter

[![This is how it should look][1]][1]


  [1]: https://i.stack.imgur.com/GSCry.png

Add border to a Container with borderRadius in Flutter

I am new to Flutter, I started Flutter last week, And now I want to make a simple Xylophone app. I created the UI successfully and made a function `playSound(int soundNumber)` but when I call this function for playing sound, it gives me this error.

    **The following _TypeError was thrown building Body(dirty, state: _BodyState#051c2):
    type &#39;_MaterialStatePropertyAll&lt;dynamic&gt;&#39; is not a subtype of type &#39;MaterialStateProperty&lt;Color?&gt;?&#39;**

Here&#39;s the code I wrote for `playSound(int soundNumber)` function.

    void playSound(int soundNumber) {
    final player = AudioCache();
    player.play(&#39;note$soundNumber.wav&#39;);}

    Expanded buildPlayButton({MaterialStateProperty color, int soundNumber}){
    return Expanded(
      child: ElevatedButton(
        onPressed: () {
          playSound(soundNumber);
        },
        style: ButtonStyle(
          backgroundColor: color,
        ),
      ),
    );}

Here is the point where I am calling this function.

    Widget build(BuildContext context) {
    return Column(
      crossAxisAlignment: CrossAxisAlignment.stretch,
      children: &lt;Widget&gt;[
        buildPlayButton(color: MaterialStateProperty.all(Colors.red), soundNumber: 1),
        buildPlayButton(color: MaterialStateProperty.all(Colors.orangeAccent), soundNumber: 2),
        buildPlayButton(color: MaterialStateProperty.all(Colors.yellow), soundNumber: 3),
        buildPlayButton(color: MaterialStateProperty.all(Colors.indigo), soundNumber: 4),
        buildPlayButton(color: MaterialStateProperty.all(Colors.blue), soundNumber: 5),
        buildPlayButton(color: MaterialStateProperty.all(Colors.lightGreenAccent), soundNumber: 6),
        buildPlayButton(color: MaterialStateProperty.all(Colors.green), soundNumber: 7),
      ],
    );
    }

How to call this function because it gives me the above-mentioned error?

Content Type	Original Author	Original Content on Stackoverflow
Question	sphoenix	View Question on Stackoverflow
Solution 1 - Flutter	CopsOnRoad	View Answer on Stackoverflow
Solution 2 - Flutter	biniyam112	View Answer on Stackoverflow
Solution 3 - Flutter	MBK	View Answer on Stackoverflow
Solution 4 - Flutter	I Made Mudita	View Answer on Stackoverflow
Solution 5 - Flutter	enarcee	View Answer on Stackoverflow

Flutter: InkWell vs GestureDetector: what is the difference?

Flutter Problem Overview

Flutter Solutions

Solution 1 - Flutter

Solution 2 - Flutter

Solution 3 - Flutter

Visual Difference
https://i.stack.imgur.com/XfEpx.gif" width="400">

Solution 4 - Flutter

Solution 5 - Flutter

Equal widths of subviews with SwiftUI

Difference between "detach()" and "with torch.nograd()" in PyTorch?

Attributions

Flutter Problem Overview

Flutter Solutions

Solution 1 - Flutter

Solution 2 - Flutter

Solution 3 - Flutter

Visual Difference https://i.stack.imgur.com/XfEpx.gif" width="400">

Solution 4 - Flutter

Solution 5 - Flutter

Equal widths of subviews with SwiftUI

Difference between "detach()" and "with torch.nograd()" in PyTorch?

Attributions

Visual Difference
https://i.stack.imgur.com/XfEpx.gif" width="400">