Realm是一个能够代替SQLite和Core Data的手机数据库。使用 C++ 内核，所以效率非常的高，是 sqlite 的近几倍。

特性：

• Mobile-first: Realm is the first database built from the ground up to run directly inside phones, tablets and wearables.
• Simple: Data is directly exposed as objects and queryable by code, removing the need for ORM's riddled with performance & maintenance issues. Plus, we've worked hard to keep our API down to very few classes: most of our users pick it up intuitively, getting simple apps up & running in minutes.
• Modern: Realm supports easy thread-safety, relationships & encryption.
• Fast: Realm is faster than even raw SQLite on common operations, while maintaining an extremely rich feature set.

Realm 中文文档：http://djyde.github.io/2014/10/17/realm-doc-in-chinese.html

Realm realm = Realm.getInstance(this);    // All writes are wrapped in a transaction  // to facilitate safe multi threading  realm.beginTransaction();    // Add a person  Person person = realm.createObject(Person.class);  person.setName("Young Person");  person.setAge(14);    realm.commitTransaction();    RealmResults<User> result = realm.where(User.class)                                   .greaterThan("age", 10)  // implicit AND                                   .beginGroup()                                        .equalTo("name", "Peter")                                        .or()                                        .contains("name", "Jo")                                   .endGroup()                                   .findAll();

项目主页：http://www.open-open.com/lib/view/home/1413557451497