Firebase Class with Crud Operation

Firebase Class with Crud Operation

performing CRUD operations using Firebase Realtime Database in an Android app using Java:

1. Create a model class for your data

javaCopy codepublic class Person {
    private String id;
    private String name;
    private int age;

    public Person() {
        // Required empty constructor
    }

    public Person(String id, String name, int age) {
        this.id = id;
        this.name = name;
        this.age = age;
    }

    // Getters and setters

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    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;
    }
}

1. Initialize Firebase in your activity or fragment

public class MainActivity extends AppCompatActivity {

    private FirebaseDatabase database;
    private DatabaseReference myRef;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        // Initialize Firebase
        database = FirebaseDatabase.getInstance();
        myRef = database.getReference("people");
    }
}

1. Insert data

// Generate a new id for the person
String id = myRef.push().getKey();

Person person = new Person(id, "John Doe", 25);

myRef.child(id).setValue(person);

1. Read data

// Read all people
myRef.addValueEventListener(new ValueEventListener() {
    @Override
    public void onDataChange(DataSnapshot dataSnapshot) {
        List<Person> people = new ArrayList<>();

        for (DataSnapshot personSnapshot : dataSnapshot.getChildren()) {
            Person person = personSnapshot.getValue(Person.class);
            people.add(person);
        }

        // Do something with the list of people
    }

    @Override
    public void onCancelled(DatabaseError databaseError) {
        // Handle database error
    }
});

// Read a single person by id
String id = "person1";
myRef.child(id).addListenerForSingleValueEvent(new ValueEventListener() {
    @Override
    public void onDataChange(DataSnapshot dataSnapshot) {
        Person person = dataSnapshot.getValue(Person.class);

        // Do something with the person
    }

    @Override
    public void onCancelled(DatabaseError databaseError) {
        // Handle database error
    }
});

1. Update data

String id = "person1";

// Create a new person object with the updated data
Person updatedPerson = new Person(id, "Jane Doe", 30);

myRef.child(id).setValue(updatedPerson);

1. Delete data

String id = "person1";

myRef.child(id).removeValue();

retrieves all person data from Firebase Realtime Database:

myRef.addValueEventListener(new ValueEventListener() {
    @Override
    public void onDataChange(DataSnapshot dataSnapshot) {
        List<Person> people = new ArrayList<>();

        for (DataSnapshot personSnapshot : dataSnapshot.getChildren()) {
            Person person = personSnapshot.getValue(Person.class);
            people.add(person);
        }

        // Do something with the list of people
    }

    @Override
    public void onCancelled(DatabaseError databaseError) {
        // Handle database error
    }
});

deletes all person data from Firebase Realtime Database:

myRef.removeValue(new DatabaseReference.CompletionListener() {
    @Override
    public void onComplete(DatabaseError databaseError, DatabaseReference databaseReference) {
        if (databaseError != null) {
            // Handle the error
        } else {
            // The data has been removed successfully
        }
    }
});

inserts an ArrayList of person model data into Firebase Realtime Database:

ArrayList<Person> people = // Your ArrayList of Person objects
DatabaseReference myRef = FirebaseDatabase.getInstance().getReference("people");

for (Person person : people) {
    String key = myRef.push().getKey();
    myRef.child(key).setValue(person, new DatabaseReference.CompletionListener() {
        @Override
        public void onComplete(DatabaseError databaseError, DatabaseReference databaseReference) {
            if (databaseError != null) {
                // Handle the error
            } else {
                // The data has been inserted successfully
            }
        }
    });
}