How to check if data exist in Android Firebase Database

In this android programming source code example, we are going to check if data exist in Android Firebase Database

You can copy and adopt this source code example to your android project without reinventing the wheel.

Below is a step by step source code to check if data exist in Android Firebase Database.

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:padding="15dp"
    android:background="#CACACA">

    <TextView
        android:id="@+id/title"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="title"
        android:textSize="20sp"
        android:layout_marginTop="90dp"/>

    <View
        android:id="@+id/view1"
        android:layout_width="match_parent"
        android:layout_height="2sp"
        android:layout_below="@id/title"
        android:background="@color/colorAccent"/>

    <TextView
        android:id="@+id/body"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="body"
        android:textSize="30sp"
        android:layout_below="@id/view1"/>

</RelativeLayout>

MainActivity.java

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.widget.TextView;
import android.widget.Toast;

import com.google.firebase.database.DataSnapshot;
import com.google.firebase.database.DatabaseError;
import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;
import com.google.firebase.database.Query;
import com.google.firebase.database.ValueEventListener;

public class FirebaseActivity11 extends AppCompatActivity {
    private TextView title;
    private TextView body;
    private DatabaseReference mDatabase;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_firebase11);
        title = (TextView)findViewById(R.id.title);
        body = (TextView)findViewById(R.id.body);
        mDatabase = FirebaseDatabase.getInstance().getReference().child("AndroidView");
        Query query = mDatabase.orderByChild("title");
        query.addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(DataSnapshot dataSnapshot) {
                if(dataSnapshot.exists()){
                    for(DataSnapshot readData: dataSnapshot.getChildren()){
                        Data data = readData.getValue(Data.class);
                        title.setText(data.getTitle());
                        body.setText(data.getContent());
                    }
                }else{
                    Toast.makeText(FirebaseActivity11.this,"Data Empty",Toast.LENGTH_LONG).show();
                }
            }
            @Override
            public void onCancelled(DatabaseError databaseError) {
                Toast.makeText(FirebaseActivity11.this,databaseError.getMessage(),Toast.LENGTH_LONG).show();
            }
        });
    }
}

Data.java

app/build.gradle

implementation 'com.google.firebase:firebase-core:16.0.9'
implementation 'com.google.firebase:firebase-database:17.0.0'

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