firebase-database

FirebaseRealtime database with Android

Add the Realtime Database in Android

  1. Complete the Installation and setup to connect your app to Firebase.

This will create the project in Firebase.

  1. Add the dependency for Firebase Realtime Database to your module-level build.gradle file:

    compile ‘com.google.firebase:firebase-database:9.2.1’

  2. Configure Firebase Database Rules

Now you are ready to work with the Realtime Database in Android.

For example you write a Hello World message to the database under the message key.

// Write a message to the database
FirebaseDatabase database = FirebaseDatabase.getInstance();
DatabaseReference myRef = database.getReference("message");

myRef.setValue("Hello, World!");

Using setValue to save data

ThesetValue() method overwrites data at the specified location, including any child nodes.

You can use this method to:

  1. Pass types that correspond to the available JSON types as follows:
  • String
  • Long
  • Double
  • Boolean
  • Map<String, Object>
  • List
    1. Pass a custom Java object, if the class that defines it has a default constructor that takes no arguments and has public getters for the properties to be assigned.

    This is an example with a CustomObject.
    First define the object.

    @IgnoreExtraProperties
public class User {

    public String username;
    public String email;

    public User() {
        // Default constructor required for calls to DataSnapshot.getValue(User.class)
    }

    public User(String username, String email) {
        this.username = username;
        this.email = email;
    }

    Then get the Database reference and set the value:

       User user = new User(name, email);
   DatabaseReference mDatabase mDatabase = FirebaseDatabase.getInstance().getReference();
   mDatabase.child("users").child(userId).setValue(user);

    Example for data insert or data retrieve from Firebase

    Get value/s from firebase

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