Stack API

SnapshotStateStack
Voyager is backed by a SnapshotStateStack:
Implementation of Stack that can be observed and snapshot
Internally uses a SnapshotStateList​
State-aware: content change triggers a recomposition​
You will use it to navigate forward (push, replace, replaceAll) and backwards (pop, popAll, popUntil), but the SnapshotStateStack can also be used as a regular collection outside the Navigator.
val stack = mutableStateStackOf("🍇", "🍉", "🍌", "🍐", "🥝", "🍋")
// 🍇, 🍉, 🍌, 🍐, 🥝, 🍋
​
stack.lastItemOrNull
// 🍋
​
stack.push("🍍")
// 🍇, 🍉, 🍌, 🍐, 🥝, 🍋, 🍍
​
stack.pop()
// 🍇, 🍉, 🍌, 🍐, 🥝, 🍋
​
stack.popUntil { it == "🍐" }
// 🍇, 🍉, 🍌, 🍐
​
stack.replace("🍓")
// 🍇, 🍉, 🍌, 🍓
​
stack.replaceAll("🍒")
// 🍒
You can also create a SnapshotStateStack through rememberStateStack(), it will restore the values after Activity recreation.
Events
Whenever the content changes, the SnapshotStateStack will emit a StackEvent. Use the stack.lastEvent to get the most recent one.
The available events are:
Push: whenever push is called
Replace: whenever replace and replaceAll are called
Pop: whenever pop and popAll are called
Idle: default event
This is very useful for deciding which transition to make.
Sample
Source code here.

Hilt integration

State restoration

Last modified 11mo ago