public final class SyncedStore

A small key/value store the platform carries between the devices one person signed in to, without them ever being in the same room.

This is the slow, patient half of continuity. com.codename1.continuity.Continuity hands the current activity to a device that is here, now; this keeps a handful of durable settings – which theme, which sort order, which tutorial they already dismissed, the id of the document they are working through – in step across everything they own.

SyncedStore.put("sortOrder", "byDate");
String order = SyncedStore.get("sortOrder", "byName");

What it is not

Not storage. Not a database, not a cache, and not a place for anything the app cannot cheerfully do without: the platform decides when to sync, the user can turn the whole mechanism off, and a device that has never been online has an empty store. Treat every read as “the value, or the default” – which is why there is no read without a default.

Not secret. The contents leave the device and are held by the platform on the user’s behalf. Credentials belong in com.codename1.security.SecureStorage.

Not large. The platform imposes a total size and a key count, both small; put reports a failure to write rather than pretending it stored something.

What it costs

Referencing this package is what makes an iOS build ask for the entitlement that gives the app a synced store, which in turn requires the capability to be enabled on the App ID. That is why it is a package of its own: an app that wants continuation to a nearby device and nothing else should not have to arrange an entitlement to get it. Where the platform has no such store – Android, desktop, the browser – isSupported() is false and every call here is an inert no-op, so the sensible shape is a synced value with a local default behind it.

Threading

Called on the event dispatch thread, like the rest of the toolkit. Codename One is single threaded by design – one thread on each side of a native boundary, marshalled at the boundary rather than locked – and this class follows that rule rather than making an exception to it.

It is worth stating because the simulation behind isSupported() == true on a desktop keeps its key index as a second stored value: two threads writing different NEW keys at once would each read that index, add their own key, and write it back, so one of them would vanish from keys() while its value stayed readable by name. The platform stores have no such structure and no such exposure. The answer is the toolkit’s answer everywhere else – call it from the event thread, and use com.codename1.ui.Display#callSerially(Runnable) if you are on another one – not a lock inside a framework that does not have them.