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Flutter – Outputting Widgets Conditionally

Flutter is a popular mobile app development framework that allows developers to create beautiful and high-performance mobile applications for both Android and iOS platforms. It offers a wide range of widgets and tools that make it easy for developers to build and design user interfaces.

One of the most powerful features of Flutter is its ability to output widgets conditionally. This means that developers can choose which widgets to display based on certain conditions, such as the state of the application or the data that is being displayed.

In this article, we will explore the different ways that developers can output widgets conditionally in Flutter and provide examples of how this can be implemented in real-world applications.

Using the Conditional Operator

The conditional operator is a shorthand way of writing an if-else statement in Flutter. It is often used to output widgets conditionally based on a boolean value.

The syntax of the conditional operator is as follows:

condition ? widget1 : widget2

If the condition is true, then widget1 is displayed. Otherwise, widget2 is displayed.

Here is an example:

bool isButtonEnabled = true;

return Column(
  children: [
    isButtonEnabled ? ElevatedButton(
      onPressed: () { /* do something */ },
      child: Text('Enabled'),
    ) : ElevatedButton(
      onPressed: null,
      child: Text('Disabled'),
    ),
  ],
);

In this example, an ElevatedButton widget is displayed conditionally based on the value of the isButtonEnabled boolean variable. If it is true, then an enabled button is displayed. Otherwise, a disabled button is displayed.

Using the If-Else Statement

The if-else statement is a more verbose way of outputting widgets conditionally in Flutter. It allows developers to specify more complex conditions and actions.

The syntax of the if-else statement is as follows:

if (condition) {
  // code to execute if condition is true
} else {
  // code to execute if condition is false
}

Here is an example of how this can be used to output widgets conditionally:

bool isLoggedIn = false;

return Column(
  children: [
    if (isLoggedIn)
      Text('Welcome back!'),
    else
      ElevatedButton(
        onPressed: () { /* do something */ },
        child: Text('Log in'),
      ),
  ],
);

Flutter Conditional Show Widget using custom library

What is a Conditional Show Widget?

A Conditional Show Widget is a widget in Flutter that allows you to show or hide a child widget based on a condition. The condition can be any expression that evaluates to a boolean value.

Using the Flutter Conditional Show Widget

To use the Flutter Conditional Show Widget, you will first need to import the package into your project. You can do this by adding the following code to your pubspec.yaml file:

dependencies:
  flutter:
    sdk: flutter
  conditional_builder: ^1.0.0

Once you have imported the package, you can start using the Conditional Show Widget.

Here is an example of how to use the widget:

ConditionalBuilder(
  condition: true,
  builder: (BuildContext context) => Text('This text will be shown'),
  fallback: (BuildContext context) => Text('This text will be hidden'),
)

In the above example, the Conditional Show Widget will show the text “This text will be shown” because the condition is set to true. If the condition were set to false, the widget would show the fallback text “This text will be hidden”.

Advanced Usage

The Flutter Conditional Show Widget can be used in more advanced scenarios as well. For example, you can use it to show or hide entire sections of your UI based on user input. Here is an example of how to do this:

bool _showSection = false;

ConditionalBuilder(
  condition: _showSection,
  builder: (BuildContext context) => Column(
    children: [
      Text('Section 1'),
      Text('Section 2'),
      Text('Section 3'),
    ],
  ),
  fallback: (BuildContext context) => Container(),
)

RaisedButton(
  onPressed: () {
    setState(() {
      _showSection = !_showSection;
    });
  },
  child: Text('Toggle Section'),
)

In the above example, the Conditional Show Widget will show a column of text widgets when the _showSection variable is set to true. The RaisedButton below the widget allows the user to toggle the _showSection variable and show or hide the column of text widgets.

Conclusion

In conclusion, the Flutter Conditional Show Widget is a powerful tool that can be used to show or hide widgets based on conditions. By leveraging this widget, you can create dynamic, responsive, and personalized user interfaces that are tailored to your users’ needs. We hope that this guide has been helpful in showing you how to use the Flutter Conditional Show Widget effectively.