Realm is a mobile database that is faster than SQLite and supports in-memory databases and custom migrations. It can replace SQLite in mobile applications. Realm supports object mapping with models that extend RealmObject and relationships between objects. Queries can be performed on object properties using conditions and sorting. Objects can be inserted, updated, and deleted from Realm asynchronously in transactions to avoid blocking the UI.

1. Realm JAVA 2.2.0
Build better apps, faster apps
Author: Doi Thanh Thinh
Savvycom JSC
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2. SQLite problems
• Queries too slow
• Complex
relationships
• Nest SELECT, JOIN
• Migration
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3. SQLite problems
No-SQL SQLite
A
B
D
G
C
FE
Realm.getA().getC().getF();
SELECT user.name, user.email
FROM user
INNER JOIN shop ON user.id =
shop.userid INNER JOIN city ON
user.cityid = city.id WHERE user.name =
'the flash'
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4. 1. What Realm Is
2. Compare and contrast with SQLite
3. Implement Realm
4. Example
Overview
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5.  Realm is a mobile database and a replacement
for SQLite
 Core is written in C++
 Cross platform mobile database
What Realm Is
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6.  Advantages
 Faster than SQLite
 Support in-memory database
 Custom migrating
 The Realm file can be stored encrypted on disk by standard AES-256
encryption
 Missing Features
 Auto-incrementing ids
 Compoud primary keys
Features
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7. Prerequisites
• Do not support Java outside of Android at the moment
• Android Studio >= 1.5.1
• A recent version of the Android SDK
• JDK version >=7
• Support all Android versions since API Level 9 (Android
2.3 Gingerbread & above)
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8. Benchmarks
Faster than SQLite (up to 10x speed up over raw SQLite )
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9. Benchmarks
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10. Benchmarks
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11. Step 1: Add the following class path dependency to the project level
build.gradle file.
buildscript {
repositories {
jcenter()
}
dependencies {
classpath "io.realm:realm-gradle-plugin:2.2.0"
}
}
Step 2: Apply the realm-android plugin to the top of application level
build.gradle file.
apply plugin: 'realm-android'
Installation
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12.  Models: Realm model classes are created by
extending the RealmObject base class.
public class User extends RealmObject {
private String name;
private int age;
@Ignore
private int sessionId;
// Standard getters & setters generated by your IDE…
public String getName() { return name; }
public void setName(String name) { this.name = name; }
public int getAge() { return age; }
public void setAge(int age) { this.age = age; }
public int getSessionId() { return sessionId; }
public void setSessionId(int sessionId) { this.sessionId = sessionId; }
}
Implement Realm
Custom methods:
public boolean hasLongName() {
return name.length() > 7;
}
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13.  Field types:
Supports the following field types:
boolean, byte, short, int, long, float, double, String, Date and
byte[].
The boxed types Boolean, Byte, Short, Integer, Long, Float and
Double
 @Required: used to tell Realm to enforce checks to disallow
null values
 @Ignore: a field should not be persisted to disk
 @PrimaryKey : a primary key field
 @Index will add a search index to the field
Implement Realm: Types fields
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14. Relationships
N – 1
public class Contact extends
RealmObject {
private Email email;
// Other fields…
}
N - N
public class Contact extends
RealmObject {
public RealmList<Email> emails;
// Other fields…
}
You can use this to model
both one-to-many, and
many-to-many
relationships.
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15. Conditions of Queries
 between(), greaterThan(), lessThan(), greaterThanOrEqualTo() &
lessThanOrEqualTo()
 equalTo() & notEqualTo()
 contains(), beginsWith() & endsWith()
 isNull() & isNotNull()
 isEmpty() & isNotEmpty()
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16. RealmResults<User> r = realm.where(User.class)
.greaterThan("age", 10) //implicit AND
.beginGroup()
.equalTo("name", "Peter")
.or()
.contains("name", "Jo")
.endGroup()
.findAll();
Conditions of Queries
RealmResults<User> result = realm.where(User.class).findAll();
result = result.sort("age"); // Sort ascending
result = result.sort("age", Sort.DESCENDING);
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17. Insert
Realm myRealm = Realm.getInstance(this);
Person person2 = new Person();
person2.setId("U2");
person2.setName("John");
myRealm.beginTransaction();
// copy the object to realm. Any further changes must happen on realmPerson
Person realmPerson = myRealm.copyToRealm(person2);
myRealm.commitTransaction();
Dog dog1 = myRealm.createObject(Dog.class);
// Set its fields
dog1.setId("A");
dog1.setName("Fido");
dog1.setColor("Brown");
myRealm.commitTransaction(); 17Doi Thanh Thinh - Savvycom JSC

18. realm.executeTransaction(new Realm.Transaction() {
@Override
public void execute(Realm realm) {
Dog myDog = realm.createObject(Dog.class);
myDog.setName("Fido");
myDog.setAge(1);
}
});
Dog myDog = realm.where(Dog.class).equalTo("age", 1).findFirst();
realm.executeTransaction(new Realm.Transaction() {
@Override
public void execute(Realm realm) {
Dog myPuppy = realm.where(Dog.class).equalTo("age", 1).findFirst();
myPuppy.setAge(2);
}
});
myDog.getAge(); // => 2
Auto-Updating
Auto Update Realtime
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19. Example
public class Person extends
RealmObject {
private String id;
private String name;
private RealmList<Dog> dogs;
// getters and setters
}
public class Dog extends RealmObject {
private String id;
private String name;
private String color;
// getters and setters
}
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20. Example
// persons => [U1,U2]
RealmResults<Person> persons = realm.where(Person.class)
.equalTo("dogs.color", "Brown")
.findAll();
// r1 => [U1,U2]
RealmResults<Person> r1 = realm.where(Person.class)
.equalTo("dogs.name", "Fluffy")
.equalTo("dogs.color", "Brown")
.findAll();
// r2 => [U2]
RealmResults<Person> r2 = realm.where(Person.class)
.equalTo("dogs.name", "Fluffy")
.findAll()
.where()
.equalTo("dogs.color", "Brown")
.findAll();
.where()
.equalTo("dogs.color", "Yellow")
.findAll();
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21. Insert/Update
Asynchronous Transactions:
realm.executeTransactionAsync(new Realm.Transaction() {
@Override
public void execute(Realm bgRealm) {
User user = bgRealm.createObject(User.class);
user.setName("John");
user.setEmail("john@corporation.com");
}
}, new Realm.Transaction.OnSuccess() {
@Override
public void onSuccess() {
// Transaction was a success.
}
}, new Realm.Transaction.OnError() {
@Override
public void onError(Throwable error) {
// Transaction failed and was automatically canceled.
}
});
Avoid blocking the UI thread
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22. Delete
// obtain the results of a query
final RealmResults<Dog> results = realm.where(Dog.class).findAll();
// All changes to data must happen in a transaction
realm.executeTransaction(new Realm.Transaction() {
@Override
public void execute(Realm realm) {
// remove single match
results.deleteFirstFromRealm();
results.deleteLastFromRealm();
// remove a single object
Dog dog = results.get(5);
dog.deleteFromRealm();
// Delete all matches
results.deleteAllFromRealm();
}
});
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23. JSON
• It is possible to add RealmObjects represented as JSON directly to Realm .
they are represented as a String, a JSONObject or an InputStream
• Single object is added through Realm.createObjectFromJson()
• lists of objects are added using Realm.createAllFromJson().
// A RealmObject that represents a city
public class City extends RealmObject {
private String city;
private int id;
// getters and setters left out ...
}
// Insert from a string
realm.executeTransaction(new Realm.Transaction() {
@Override
public void execute(Realm realm) {
realm.createObjectFromJson(City.class, "{ city: "Copenhagen", id: 1 }");
}
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24. Demo
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25. Resources
Official Site for Realm
https://realm.io/
Realm Full API for Java
http://realm.io/docs/java/latest/api/
Realm Browser:
https://github.com/realm/realm-cocoa/tree/master/tools/RealmBrowser
Github:
https://github.com/thinhdt/DemoRealm
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