Error handling for network calls in Flutter - UI Render Trace

Component - Error handling for network calls

This UI component shows how a Flutter app handles errors during network calls. It tries to fetch data from the internet and shows either the data, a loading spinner, or an error message with a retry button.

Widget Tree

Scaffold
├── AppBar
└── body: Center
    └── Column
        ├── Expanded
        │   └── child: content (Text or CircularProgressIndicator)
        └── ElevatedButton (Retry)

The Scaffold provides the basic page structure with a top bar (AppBar). The body centers a Column that holds the main content area and a retry button below. The content area expands to fill space and shows either loading spinner, fetched text, or error message.

Render Trace - 7 Steps

Step 1: Scaffold

Step 2: Center

Step 3: Column

Step 4: Expanded

Step 5: ElevatedButton

Step 6: Expanded

Step 7: Expanded

State Change - Re-render

Trigger:User taps 'Retry' button or app starts fetching data

Before

Loading spinner visible, no data or error shown

→

After

Either data text shown if fetch succeeds or error message shown if fetch fails

Re-renders:Expanded content area and ElevatedButton remain, only content child widget re-renders

UI Quiz - 3 Questions

What does the CircularProgressIndicator show in this UI?

A That the data was loaded successfully

B That there was an error fetching data

C That the app is loading data from the network

D That the retry button is disabled

Key Insight

Handling network errors in mobile apps means showing clear feedback: a spinner while loading, an error message if something goes wrong, and a retry option. This keeps users informed and lets them try again easily.