ViewModel이 회전 후에도 유지되는 이유

Rotate the screen and Android destroys your Activity, wiping any state you stored in it. Your counter, text, and scroll position all vanish. 😵

Rotation is one of many configuration changes: theme switches, locale changes, and window resizing all recreate your screen the same way.

A ViewModel is a class built to hold UI state that outlives the Activity it serves, so a rotation no longer throws your data away.

The ViewModel is scoped to the screen’s lifecycle owner, so the same instance is handed back to the recreated Activity instead of a fresh one.

Android keeps the ViewModel in a retained store across the configuration change, then reconnects it to your brand-new Activity automatically.

A ViewModel lives until the screen is truly finished. When the user navigates away for good, onCleared() runs so you can release resources.

The ViewModel survives rotation but not process death. For that, pair it with SavedStateHandle so critical values can be restored later.

You get ViewModel support from the lifecycle libraries. Add the lifecycle-viewmodel-compose artifact so Compose can obtain one easily.

Beyond survival, a ViewModel keeps logic out of your UI. Your Composables stay focused on drawing while the ViewModel owns the state.

Think of the ViewModel as a quiet backstage manager: the Activity comes and goes, but the manager keeps your show’s state ready to perform again.

Surviving rotation means users never lose progress mid-task. That reliability is the foundation every robust Compose app is built on. ✨

Test your grasp of why a ViewModel outlives a rotation.

Rotation recreates your Activity, but a ViewModel survives configuration changes and reattaches, keeping UI state intact and logic out of the UI.