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¶ ViewModel과 Lifecycle 기초
¶ Activity의 Lifecycle
¶ Activity의 Lifecycle
ref) https://developer.android.com/guide/components/activities/activity-lifecycle#alc
¶ onSaveInstanceState에 의한 상태 보존
override fun onSaveInstanceState(outState: Bundle) {
super.onSaveInstanceState(outState)
outState.putString("key", "value")
}
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
if (savedInstanceState != null) {
val value = savedInstanceState.getString("key")
}
}
When sending data via an intent, you should be careful to limit the data size to a few KB. Sending too much data can cause the system to throw a TransactionTooLargeException exception.
¶ Jetpack ViewModel의 제안
ref) https://developer.android.com/topic/libraries/architecture/viewmodel
¶ Saved State module 사용하기
| ViewModel | Saved instance state | Persistent storage | |
|---|---|---|---|
| Storage location | in memory | serialized to disk | on disk or network |
| Survives configuration change | Yes | Yes | Yes |
| Survives system-initiated process death | No | Yes | Yes |
| Survives user complete activity dismissal/onFinish() | No | No | Yes |
| Data limitations | complex objects are fine, but space is limited by available memory | only for primitive types and simple, small objects such as String | only limited by disk space or cost / time of retrieval from the network resource |
| Read/write time | quick (memory access only) | slow (requires serialization/deserialization and disk access) | slow (requires disk access or network transaction) |