Passing data between activities in Android Kotlin - UI Render Trace

Component - Passing data between activities

This UI component demonstrates how to send data from one screen (activity) to another in an Android app using Kotlin. It shows a simple form where you enter text, press a button, and the next screen displays the entered text.

Widget Tree

Activity1 (MainActivity)
├── EditText (input field)
└── Button (send data)

Activity2 (DisplayActivity)
└── TextView (shows received data)

The first screen (MainActivity) has an input box and a button arranged vertically. When the button is clicked, it opens the second screen (DisplayActivity), which shows the text sent from the first screen.

Render Trace - 3 Steps

Step 1: MainActivity

Step 2: Button (in MainActivity)

Step 3: DisplayActivity

State Change - Re-render

Trigger:User types text in EditText and clicks the Send button

Before

MainActivity shows empty input field; DisplayActivity not started

→

After

DisplayActivity opens showing the text entered in MainActivity

Re-renders:DisplayActivity UI rebuilds to show the passed data; MainActivity remains unchanged

UI Quiz - 3 Questions

How does MainActivity send data to DisplayActivity?

A By directly modifying DisplayActivity's TextView

B By putting data into Intent extras before starting DisplayActivity

C By saving data in a global variable

D By using a database to share data

Key Insight

Passing data between activities in Android is done by attaching data to an Intent as extras. This keeps screens independent and allows smooth data transfer. Always use Intent extras for small data like strings or numbers to keep your app simple and responsive.