Interface HealthBackgroundListener

public interface HealthBackgroundListener

Receives health-store changes even after the app's process has been killed and relaunched. Registered by class with HealthStore.subscribe(SubscriptionRequest,Class), mirroring LocationManager.setBackgroundLocationListener(Class).

Requirements on the implementing class

It must be a public top-level class with a public no-argument constructor. The framework instantiates it fresh for every delivery, including after a cold relaunch, so do not keep state in fields and do not assume any of your app's initialization has run.

What you may do inside

You are called on the EDT, but on iOS there may be no visible UI at all -- the OS woke the app purely to hand you data. Check Display.getInstance().isMinimized() before touching anything visual, and keep the work small: HealthChangeBatch.getDeadlineMillis() is around five seconds on a background relaunch. Accumulate into Preferences or Storage and do the real work on next foreground.

public class StepWatcher implements HealthBackgroundListener {
    public void healthDataChanged(HealthChangeBatch batch) {
        if (batch.isResyncRequired()) {
            Preferences.set("stepsWatermark", 0L);
            return;
        }
        long added = 0;
        for (HealthSample s : batch.getAdded()) {
            added += (long) ((QuantitySample) s).getValue(HealthUnit.COUNT);
        }
        Preferences.set("pendingSteps",
                Preferences.get("pendingSteps", 0L) + added);
    }
}

You do not need to keep the class reachable

The build server scans for implementations of this interface and generates a factory that constructs each one with a direct new expression, then registers it during app startup. Because the generated binding is a real reference rather than a string, dead-code elimination and obfuscation both follow it correctly -- so unlike some older callback APIs in this framework, there is nothing you have to do to stop your listener being stripped from a release build.

See HealthBackgroundListenerFactory.

Method Summary

Modifier and Type	Method	Description
void	healthDataChanged(HealthChangeBatch batch)	Called with the changes accumulated since the last delivery.

Method Details

healthDataChanged

void healthDataChanged(HealthChangeBatch batch)

Called with the changes accumulated since the last delivery.