Local Data Base Creation

step 1:

Class name;Contact

public class Contact {

//private variables    int _id;
    String _name;
    String _phone_number;

    // Empty constructor    public Contact(){

    }
    // constructor    public Contact(int id, String name, String _phone_number){
        this._id = id;
        this._name = name;
        this._phone_number = _phone_number;
    }

    // constructor    public Contact(String name, String _phone_number){
        this._name = name;
        this._phone_number = _phone_number;
    }
    // getting ID    public int getID(){
        return this._id;
    }

    // setting id    public void setID(int id){
        this._id = id;
    }

    // getting name    public String getName(){
        return this._name;
    }

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

    // getting phone number    public String getPhoneNumber(){
        return this._phone_number;
    }

    // setting phone number    public void setPhoneNumber(String phone_number){
        this._phone_number = phone_number;
    }
}

step 2:

Class name: DB Helper

public class Contact {

    //private variables    int _id;
    String _name;
    String _phone_number;

    // Empty constructor    public Contact(){

    }
    // constructor    public Contact(int id, String name, String _phone_number){
        this._id = id;
        this._name = name;
        this._phone_number = _phone_number;
    }

    // constructor    public Contact(String name, String _phone_number){
        this._name = name;
        this._phone_number = _phone_number;
    }
    // getting ID    public int getID(){
        return this._id;
    }

    // setting id    public void setID(int id){
        this._id = id;
    }

    // getting name    public String getName(){
        return this._name;
    }

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

    // getting phone number    public String getPhoneNumber(){
        return this._phone_number;
    }

    // setting phone number    public void setPhoneNumber(String phone_number){
        this._phone_number = phone_number;
    }
}

step 3:

Class name:MainActivity

import android.content.Intent;
import android.support.design.widget.FloatingActionButton;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.AdapterView;
import android.widget.GridView;
import android.widget.Toast;
import java.util.List;

public class MainActivity extends AppCompatActivity {

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

       DBHelper db=new DBHelper(getApplicationContext());

        /**         * CRUD Operations         * */       
 // Inserting Contacts       
        Log.d("Insert: ", "Inserting ..");
        db.addContact(new Contact("Ravi", "9100000000"));
        db.addContact(new Contact("Srinivas", "9199999999"));
        db.addContact(new Contact("Tommy", "9522222222"));
        db.addContact(new Contact("Karthik", "9533333333"));

        // Reading all contacts       Log.d("Reading: ", "Reading all contacts..");
        List<Contact> contacts = db.getAllContacts();
          for (Contact cn : contacts) {
String log = "Id: "+cn.getID()+" ,Name: " + cn.getName() + " ,Phone: " + cn.getPhoneNumber();
            //Writing Contacts to log          
         Log.d("Name: ", log);
        }

    }
}