fLUTTER_LAB2

What is the primary difference between a stateful and a stateless widget in Flutter?

• Stateful widgets never change; stateless widgets can change
• Stateful widgets can change due to user interaction; stateless widgets cannot
• Stateful widgets are only used for layout; stateless widgets handle logic
• Stateful widgets use a single class; stateless widgets use two classes

Answer explanation

A stateful widget is dynamic and can change its appearance in response to user interactions or data changes

Which Flutter widget is an example of a stateless widget?

• TextField
• Checkbox
• Icon
• Slider

Answer explanation

Icon is a stateless widget because it does not change its appearance once built

What does the setState() method do in a stateful widget?

• Builds the widget
• Notifies the framework to redraw the widget
• Initializes the widget's state
• Creates a new State object

Answer explanation

Calling setState() notifies the Flutter framework that the widget's state has changed

Which of the following is a required class when implementing a custom stateful widget?

• StatelessWidget
• StatefulWidget
• State
• Widget

Answer explanation

A custom stateful widget requires a subclass of StatefulWidget to define the widget and a subclass of State to manage its state.

What is the purpose of the build() method in the State class?

• To initialize the widget's state
• To define the widget's user interface
• To handle user interactions
• To store mutable data

Answer explanation

The build() method in the State class defines the widget's user interface by returning a widget tree.

Which property of ElevatedButton is used to handle a tap event?

• onChanged
• onPressed
• onTap
• onClick

Answer explanation

The onPressed property of ElevatedButton defines the callback function that handles tap events.

Which widget is used to control a TextField in the stateful widget example with a text field?

• TextController
• TextEditingController
• InputController
• FieldController

Answer explanation

TextEditingController is used to control the TextField

What does the changeColor function do in the color-changing exercise?

• Changes the text color
• Changes the app bar color
• Changes the container's background color
• Changes the button's color

Answer explanation

The changeColor function in the exercise changes the background color of a container from yellow to red when the FloatingActionButton is pressed.

Which of the following widgets is stateful?

• Icon
• Text
• Slider
• IconButton

Answer explanation

Slider is a stateful widget because it can change its value in response to user interactions

In the text field example, when is the displayText updated?

• When the user types in the TextField
• When the ElevatedButton is pressed
• When the app starts
• When the TextField is focused

Answer explanation

The displayText is updated when the ElevatedButton is pressed