Firebase Docs Reference Transaction.Function public static interface Transaction.Function An interface for providing code to be executed within a transaction context. See Also runTransaction(Function) Public Method Summary abstract TResult apply(Transaction transaction) Public Methods public abstract TResult apply (Transaction transaction) Throws FirebaseFirestoreException Except as otherwise noted, the content of this page is licensed under the Creative Commons Attribution 3.0 License, and code samples are licensed under the Apache 2.0 License. For details, see our Site Policies. Java is a registered trademark of Oracle and/or its affiliates. Last updated May 23, 2018.