How to chain Android Firebase Database Query

In this android programming source code example, we are going to chain Android Firebase Database Query.

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 chain Android Firebase Database Query.

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 FirebaseActivity20 extends AppCompatActivity {
    private TextView title;
    private TextView body;
    private DatabaseReference mDatabase;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_firebase20);
        title = (TextView)findViewById(R.id.title);
        body = (TextView)findViewById(R.id.body);
        
        mDatabase = FirebaseDatabase.getInstance().getReference().child("AndroidView");
        Query query = mDatabase.orderByChild("title").equalTo("hello").limitToFirst(1);
        query.addListenerForSingleValueEvent(new ValueEventListener() {
            @Override
            public void onDataChange(DataSnapshot dataSnapshot) {
                for(DataSnapshot readData: dataSnapshot.getChildren()){
                    title.setText(readData.child("title").getValue().toString());
                    body.setText(readData.child("content").getValue().toString());
                }
            }
            @Override
            public void onCancelled(DatabaseError databaseError) {
                Toast.makeText(FirebaseActivity20.this,databaseError.getMessage(),Toast.LENGTH_LONG).show();
            }
        });
    }
}

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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