In this Project we will use sqlite database to store contact and show all contacts in recyclerview

and if you click on contact you will move to new Activity that is Dispaly Contact.

Step1:- MainActivity.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/recyclerView"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.5"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>

Step2:-

displayContact.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".displayContact">

    <TextView
        android:id="@+id/displayName"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="160dp"
        android:text="TextView"

        android:textSize="24sp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <TextView
        android:id="@+id/displayPhone"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginBottom="356dp"
        android:text="TextView"
        android:textSize="24sp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.5"
        app:layout_constraintStart_toStartOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>

Step3:- Item for recycler view

row.xml:-

<?xml version="1.0" encoding="utf-8"?>

<androidx.cardview.widget.CardView xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="85dp"
    xmlns:android="http://schemas.android.com/apk/res/android">

    <androidx.constraintlayout.widget.ConstraintLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <ImageView
            android:id="@+id/iconbutton"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginStart="16dp"
            android:layout_marginLeft="16dp"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent"
            app:layout_constraintVertical_bias="0.461"
            app:srcCompat="@android:drawable/sym_def_app_icon" />

        <TextView
            android:id="@+id/name"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginStart="16dp"
            android:layout_marginLeft="16dp"
            android:text="TextView"
            android:textSize="24sp"
            app:layout_constraintBottom_toTopOf="@+id/phone_number"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toEndOf="@+id/iconbutton"
            app:layout_constraintTop_toTopOf="parent" />

        <TextView
            android:id="@+id/phone_number"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginBottom="4dp"
            android:text="TextView"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toEndOf="@+id/iconbutton" />
    </androidx.constraintlayout.widget.ConstraintLayout>
</androidx.cardview.widget.CardView>

Step4:-

MainActivity.java

package guru.happylife.dbdemo;

import androidx.appcompat.app.AppCompatActivity;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;

import android.content.Context;
import android.os.Bundle;
import android.util.Log;
import android.widget.ArrayAdapter;
import android.widget.ListView;

import com.google.gson.Gson;

import java.util.ArrayList;
import java.util.List;

import guru.happylife.dbdemo.adapter.RecyclerViewAdapter;
import guru.happylife.dbdemo.data.MyDbHandler;
import guru.happylife.dbdemo.model.Contact;

public class  MainActivity extends AppCompatActivity {
 // ListView listView;
    private RecyclerView recyclerView;
    private RecyclerViewAdapter recyclerViewAdapter;
    private ArrayList<Contact> contactArrayList;
    private ArrayAdapter<String> arrayAdapter;


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

        //recycler view initialization
     recyclerView =findViewById(R.id.recyclerView);
     recyclerView.setHasFixedSize(true);
     recyclerView.setLayoutManager(new LinearLayoutManager(this));

        MyDbHandler db= new MyDbHandler(MainActivity.this);
        // adding a contact
        Contact amit=new Contact();
        amit.setId(1);
        amit.setPhoneNumber("9987548789");
        amit.setName("amit");
          db.addContact(amit);



        Gson gson = new Gson();
        String modelrespose=""+new Gson().toJson(amit).toString();

        Log.d("chekamit","amit is" +modelrespose);

//        for(int i=0;i<44;i++) {
//            db.deleteContactById(i);
//        }
         db.deleteContactById(1);


    //    ArrayList<String> contacts1 =new ArrayList<>();
        contactArrayList =new ArrayList<>();
//        listView =findViewById(R.id.listView);
        // Get all contacts
        List<Contact> contactList = db.getAllContacts();
        for(Contact contact: contactList) {
            Log.d("dbtesting", "\nId: " + contact.getId() + "\n" +
                    "Name: " + contact.getName() + "\n" +
                    "Phone Number: " + contact.getPhoneNumber() + "\n");
                 //contacts1.add(contact.getName()+"("+contact.getPhoneNumber()+")");
            contactArrayList.add(contact);
        }
      //  ArrayAdapter<String> arrayAdapter= new ArrayAdapter<>(this, android.R.layout.simple_list_item_1,contacts1);
     //   listView.setAdapter(arrayAdapter);
        //use your recyler view
        recyclerViewAdapter = new RecyclerViewAdapter(this,contactArrayList);
        recyclerView.setAdapter(recyclerViewAdapter);
        Log.d("dbtest","you have "+db.getCount()+ "records in your database");

    }
}

Step5:-

displayContact.java

package guru.happylife.dbdemo;




import androidx.appcompat.app.AppCompatActivity;

import android.content.Intent;
import android.os.Bundle;
import android.widget.TextView;

import guru.happylife.dbdemo.R;

public class displayContact extends AppCompatActivity {

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

        Intent intent = getIntent();
        String name = intent.getStringExtra("Rname");
        String phone = intent.getStringExtra("Rphone");

        TextView nameTextView = findViewById(R.id.displayName);
        nameTextView.setText(name);

        TextView phoneTextView = findViewById(R.id.displayPhone);
        phoneTextView.setText(phone);
    }
}

Step6:-

create params.java

package guru.happylife.dbdemo.params;

public class params {

    public static final int DB_VERSION=1;
     public static final String DB_NAME ="contacts_db";
     public static final String TABLE_NAME="contacts_table";


     public static final String KEY_ID="id";
     public static final String  KEY_NAME="name";
     public static final String KEY_PHONE="phone_number";
}

Step7:-

Create model class for contacts

Contact.java

package guru.happylife.dbdemo.model;

public class Contact {
     private  int id;
     private String name;
     private  String phoneNumber;

    public Contact( String name, String phoneNumber) {
        this.id = id;
        this.name = name;
        this.phoneNumber = phoneNumber;
    }

    public Contact(int id, String name, String phoneNumber) {
        this.id = id;
        this.name = name;
        this.phoneNumber = phoneNumber;
    }

    public Contact() {

    }

    public int getId() {
        return id;
    }

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

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getPhoneNumber() {
        return phoneNumber;
    }

    public void setPhoneNumber(String phoneNumber) {
        this.phoneNumber = phoneNumber;
    }
}

Step8:-

MyDbHandler.java

package guru.happylife.dbdemo.data;


import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;


import guru.happylife.dbdemo.model.Contact;
import guru.happylife.dbdemo.params.params;

import java.util.ArrayList;
import java.util.List;

public class MyDbHandler extends SQLiteOpenHelper {

    public MyDbHandler(Context context) {
        super(context, params.DB_NAME, null, params.DB_VERSION);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        String create = "CREATE TABLE " +   params.TABLE_NAME + "("
                + params.KEY_ID + " INTEGER PRIMARY KEY," + params.KEY_NAME
                + " TEXT, " + params.KEY_PHONE + " TEXT" + ")";
        Log.d("dbtestdata", "Query being run is : "+ create);
        db.execSQL(create);

    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

    }

    public void addContact(Contact contact){

        SQLiteDatabase db = this.getWritableDatabase();

        ContentValues values = new ContentValues();

        values.put(params.KEY_NAME, contact.getName());
        values.put(params.KEY_PHONE, contact.getPhoneNumber());


        db.insert(params.TABLE_NAME, null, values);
        Log.d("dbtest", "Successfully inserted");
        db.close();


    }

    public List<Contact> getAllContacts(){
        List<Contact> contactList = new ArrayList<>();
        SQLiteDatabase db = this.getReadableDatabase();

        // Generate the query to read from the database
        String select = "SELECT * FROM " + params.TABLE_NAME;
        Cursor cursor = db.rawQuery(select, null);

        //Loop through now
        if(cursor.moveToFirst()){
            do{
                Contact contact = new Contact();
                contact.setId(Integer.parseInt(cursor.getString(0)));
                contact.setName(cursor.getString(1));
                contact.setPhoneNumber(cursor.getString(2));
                contactList.add(contact);
            }while(cursor.moveToNext());
        }
        return contactList;
    }

    public int updateContact(Contact contact){
        SQLiteDatabase db = this.getWritableDatabase();

        ContentValues values = new ContentValues();
        values.put(params.KEY_NAME, contact.getName());
        values.put(params.KEY_PHONE, contact.getPhoneNumber());

        //Lets update now
        return db.update(params.TABLE_NAME, values, params.KEY_ID + "=?",
                new String[]{String.valueOf(contact.getId())});


    }



    public void deleteContactById(int id){
        SQLiteDatabase db = this.getWritableDatabase();
        db.delete(params.TABLE_NAME, params.KEY_ID +"=?", new String[]{String.valueOf(id)});
        db.close();
    }

    public void deleteContact(Contact contact){
        SQLiteDatabase db = this.getWritableDatabase();
        db.delete(params.TABLE_NAME, params.KEY_ID +"=?", new String[]{String.valueOf(contact.getId())});
        db.close();
    }

    public int getCount(){
        String query = "SELECT  * FROM " + params.TABLE_NAME;
        SQLiteDatabase db = this.getReadableDatabase();
        Cursor cursor = db.rawQuery(query, null);
        return cursor.getCount();

    }
}

Step9:-

RecyclerViewAdapter.java

package guru.happylife.dbdemo.adapter;

import android.content.Context;
import android.content.Intent;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;

import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;

import java.util.List;

import guru.happylife.dbdemo.R;
import guru.happylife.dbdemo.displayContact;
import guru.happylife.dbdemo.model.Contact;

public class RecyclerViewAdapter extends RecyclerView.Adapter<RecyclerViewAdapter.viewHolder> {

private Context context;
private List<Contact> contactList;

    public RecyclerViewAdapter(Context context, List<Contact> contactList) {
        this.context = context;
        this.contactList = contactList;
    }

    @NonNull
    @Override
    public RecyclerViewAdapter.viewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {

        View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.row,parent,false);

        return new viewHolder(view);
    }

    @Override
    public void onBindViewHolder(@NonNull RecyclerViewAdapter.viewHolder holder, int position) {
           Contact contact = contactList.get(position);

           holder.contactName.setText(contact.getName());
           holder.phoneNumber.setText(contact.getPhoneNumber());


    }

    @Override
    public int getItemCount() {
        return contactList.size();
    }

    public  class viewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {



             public TextView contactName;
             public  TextView phoneNumber;
             public ImageView iconButton;


        public viewHolder(@NonNull View itemView) {
            super(itemView);
            itemView.setOnClickListener(this);
            contactName= itemView.findViewById(R.id.name);
            phoneNumber= itemView.findViewById(R.id.phone_number);
            iconButton= itemView.findViewById(R.id.iconbutton);
            iconButton.setOnClickListener(this);

        }

        @Override
        public void onClick(View v) {

           // Log.d("ClickFromViewHolder","clicked");
            int position = this.getAdapterPosition();
            Contact contact = contactList.get(position);
            String name= contact.getName();
            String phone = contact.getPhoneNumber();
            Toast.makeText(context, "The position is"+String.valueOf(position)+"Name:"+name+"Phone"+phone, Toast.LENGTH_SHORT).show();

            Intent intent = new Intent(context, displayContact.class);
            intent.putExtra("Rname", name);
            intent.putExtra("Rphone", phone);
            context.startActivity(intent);
//            Intent intent = new Intent(context,displayContact.class);
//            intent.putExtra("Rname",name);
//            intent.putExtra("Rphone",phone);
//            context.startActivity(intent);



        }
    }

}