Radio buttons in Flutter - UI Render Trace

Component - Radio buttons

This UI component shows a group of radio buttons. Users can select only one option at a time. It is useful for choosing one item from a small list.

Widget Tree

Scaffold
├─ AppBar
│  └─ Text
└─ Column
   ├─ ListTile
   │  ├─ Radio
   │  └─ Text
   ├─ ListTile
   │  ├─ Radio
   │  └─ Text
   └─ ListTile
      ├─ Radio
      └─ Text

The Scaffold provides the basic screen structure with an AppBar at the top showing a title. The body is a Column that stacks three ListTiles vertically. Each ListTile contains a Radio button and a Text label next to it.

Render Trace - 5 Steps

Step 1: Scaffold

Step 2: Column

Step 3: ListTile (first)

Step 4: ListTile (second)

Step 5: ListTile (third)

State Change - Re-render

Trigger:User taps on a radio button

Before

selected option is 1

→

After

selected option changes to tapped radio button's value (e.g., 2)

Re-renders:Entire StatefulWidget subtree containing the Column and ListTiles re-renders to update radio button selection

UI Quiz - 3 Questions

What happens when you tap a radio button in this UI?

A Nothing changes visually

B All radio buttons become selected

C The tapped radio button becomes selected and others deselect

D The app crashes

Key Insight

Radio buttons let users pick one choice from a small set. Grouping them with the same groupValue ensures only one can be selected at a time. Using ListTile with Radio and Text creates a clean, accessible row for each option.