Part 1: CRUD Operation Using Android with Firebase Database

Let’s Start

Pre-Requirements

1. Firebase Must be Connected With Your Android Application
2. Add Below Firebase Database dependency to your app level build.gradle file. Android Studio Version is >3

implementation 'com.google.firebase:firebase-database:19.2.1'

3. Now Make Sure That You Allow Read and Write Permission True In Your Firebase Database.

For That Go to FirebaseConsole>Your Project>Database >Rules

Above Pre-Requirement is not done then follow my previous Tutorial it will Guide you in better way.

1. Insert Data On Firebase

Firebase Stored Data In Key-Value Pair , So we Have to Send Our Data into key-value Pair.

There are Two way For sending a Key-Value Pair Data to firebase

1. Directly Pass The Model Class ,here Is an Example For it.

Step 1: Create One Java Class and Define a Property That You Want to Store In Database .Here I am Creating a Rating Class inside the Model Folder .

public class Rating {
    private String id;
    private String comment;
    private String ratestar;
    public Rating(){//this constructor is required
         }
    public Rating(String id, String comment, String ratestar) {
        this.id = id;
        this.comment = comment;
        this.ratestar = ratestar;
    }
    public String getId() {
        return id;
    }
    public String getComment() {
        return comment;
    }
    public String getRatestar() {
        return ratestar;
    }
}

Step 2: Open Main Activity. And Create a instance of a firebase Database.

Something Like this,

//our database reference object
DatabaseReference databaseRatings;

Step 3: Now , Inside the OnCreate Method we Intialize this Object and assign a Firebase Database Reference like this,

//getting the reference of rating node
databaseRatings = FirebaseDatabase.getInstance().getReference("ratingList");

Here, “ ratinglist ” is a Database tableName or RootNode name , Your All data will Store into Firebase Project inside this Rating List, see the below photo

Step 4 : Now Inside OnCreate add Your Submit Button click event Or Any Button Click Submit Your data to firebase . so Create a Onclick Method and Call a Insert Method.Here getRating is a button

private  Button getRating;
//inside oncreate method
getRating.setOnClickListener(new View.OnClickListener() {

    @Override
    public void onClick(View v) {
      
        basicReadWrite();
    }
});

Step 5: Now Create a method Outside Oncreate , that will Insert Your Data to firebase.

If you need any gradle file to add for this please add and import to your main activity

public void basicReadWrite() {
try {
    final String comment = editText.getText().toString().trim();
    final String star = String.valueOf(ratingBar.getRating());;
    if (TextUtils.isEmpty(comment)) {
        editText.setError(REQUIRED);
        return;
    }
    Toast.makeText(this, "Posting...", Toast.LENGTH_SHORT).show();
    //getting a unique id using push().getKey() method
    String id = databaseRatings.push().getKey();
    Rating rating=new Rating(id,comment,star);
    //upload your class Property to Firebase database 
    databaseRatings.child(id).setValue(rating);
    editText.setText("");//empty Edit text Value
    Toast.makeText(this, "Review  added",     Toast.LENGTH_LONG).show();//displaying a success toast
}
catch (Exception ex) {
    Log.d(TAG, "Value is: " + ex);
}
}

Here , id = it is generate a unique id all time and push this unique id to your database .

databaseRatings.child(id).setValue(rating);

This Line explained as that inside Your Firebase Database create a child node and it name is same as id we have passed here . and inside this id our class data is stored . see the picture of database For Better Understand.

Inside this Picture,

review-and-ratings : it is our Project Name Or Root Node name

ratingList : It is a Reference Name or Table Name . It is a child Node For Project

Id (-M37nyejKHQYMXnccjHP) : It is a child Node For ratingList

2. Using Hashmap (Send Value Manually Using put method)

Step 1: Here We Create a User Class Inside Your Model Folder , Same as above

package com.example.firebaseauthentication.Model;
import java.util.HashMap;
public class User {
    public String UserId;
    public String UserName;
    public String Email;
    public String Password;
    private HashMap<String, String> dataMap = new HashMap<String, String>();
    public User() {
        /*Default constructor required for calls DataSnapshot.getValue(User.class)*/
    }
    public User(String UserId,String UserName, String Email,String Password) {
        this.UserId = UserId;
        this.UserName = UserName;
        this.Email = Email;
        this.Password=Password;
    }
    public HashMap<String, String> fireebaseMap(){
        return dataMap;
    }
}

You just compare Method 1 class and method 2 model class Here is some differnce .

Now All the Steps are Same as Method 1 , just change inside BasicReadwrite method is here,

public void basicReadWrite() {
try {   
final String userName=inputusername.getText().toString().trim();
final String email = inputEmail.getText().toString().trim();
final String password = inputPassword.getText().toString().trim();
    /* Here write Code for that username email and password is not empty */
   mDatabase = FirebaseDatabase.getInstance().getReference();
   User obj = new User();
   HashMap<String, String> dataMap = obj.fireebaseMap();
   dataMap.put("UserId",userKey);
   dataMap.put("UserName", userName);
   dataMap.put("Email", email); 
   dataMap.put("Password", password);
   mDatabase.child("RegisterUser").push().setValue(dataMap);
}
catch (Exception ex) {
    Log.d(TAG, "Value is: " + ex);
}
}

Here We sending Our Data in key And value Pair ,

Explanation Of Above Code

1.We Create a HashMap Object And access with the User obj ,

User obj = new User();
   HashMap<String, String> dataMap = obj.fireebaseMap();

2.Now Put key-value Pair using Hashmap. Here , left side is a Key and right side is a value.

   dataMap.put("UserId",userKey);
   dataMap.put("UserName", userName);
   dataMap.put("Email", email); 
   dataMap.put("Password", password);

3. Now Push Value to Firebase Database,

mDatabase.child("RegisterUser").push().setValue(dataMap);

Here Is a Picture That How data stored inside firebase database,

So You Can Better Understand the code of Insert.

Thanks ,

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