CRUD SQLITE operation of a database in Android

CRUD(Creation,retrieval,updation and deletion) operations in android with the help of SQLiteOpenHelper is easy to make and use. we need to follow just few steps to achieve the desired task.

1) Writing the getters and setters in java is an old art :



public class Contact {
 
    
    int _id;
    String _name;
    String _phone_number;

   
    public Contact(){

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

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

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

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

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

   
    public String getPhoneNumber(){
        return this._phone_number;
    }

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

2) creating a DatabaseHandler which extensds SQLiteOpenHelper. the code we need to write in following way :)

import java.util.ArrayList;

import java.util.List;

import android.content.ContentValues;

import android.content.Context;

import android.database.Cursor;

import android.database.sqlite.SQLiteDatabase;

import android.database.sqlite.SQLiteOpenHelper;

public class DatabaseHandler extends SQLiteOpenHelper {

    

    private static final int DATABASE_VERSION = 1;

  

    private static final String DATABASE_NAME = "contactsManager";

   

    private static final String TABLE_CONTACTS = "contacts";

    

    private static final String KEY_ID = "id";

    private static final String KEY_NAME = "name";

    private static final String KEY_PH_NO = "phone_number";

    public DatabaseHandler(Context context) {

        super(context, DATABASE_NAME, null, DATABASE_VERSION);

        context.deleteDatabase(DATABASE_NAME);

    }

   

    @Override

    public void onCreate(SQLiteDatabase db) {

        String CREATE_CONTACTS_TABLE = "CREATE TABLE " + TABLE_CONTACTS + "("

                + KEY_ID + " INTEGER PRIMARY KEY AUTOINCREMENT," + KEY_NAME + " TEXT,"

                + KEY_PH_NO + " TEXT" + ")";

        db.execSQL(CREATE_CONTACTS_TABLE);

    }

     @Override

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

        // Drop older table if existed

        db.execSQL("DROP TABLE IF EXISTS " + TABLE_CONTACTS);

        // Create tables again

        onCreate(db);

    }

    /**

     * All CRUD(Create, Read, Update, Delete) Operations

     */

  

    void addContact(Contact contact) {

        SQLiteDatabase db = this.getWritableDatabase();

        ContentValues values = new ContentValues();

        values.put(KEY_NAME, contact.getName()); // Contact Name

        values.put(KEY_PH_NO, contact.getPhoneNumber()); // Contact Phone

        // Inserting Row

        db.insert(TABLE_CONTACTS, null, values);

        db.close(); // Closing database connection

    }

   

    Contact getContact(int id) {

        SQLiteDatabase db = this.getReadableDatabase();

        Cursor cursor = db.query(TABLE_CONTACTS, new String[] { KEY_ID,

                KEY_NAME, KEY_PH_NO }, KEY_ID + "=?",

                new String[] { String.valueOf(id) }, null, null, null, null);

        if (cursor != null)

            cursor.moveToFirst();

        Contact contact = new Contact(Integer.parseInt(cursor.getString(0)),

                cursor.getString(1), cursor.getString(2));

        // return contact

        return contact;

    }

   

    public List<Contact> getAllContacts() {

        List<Contact> contactList = new ArrayList<Contact>();

        // Select All Query

        String selectQuery = "SELECT  * FROM " + TABLE_CONTACTS;

        SQLiteDatabase db = this.getWritableDatabase();

        Cursor cursor = db.rawQuery(selectQuery, null);

        // looping through all rows and adding to list

        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));

                // Adding contact to list

                contactList.add(contact);

            } while (cursor.moveToNext());

        }

        // return contact list

        return contactList;

    }

    

    public int updateContact(Contact contact) {

        SQLiteDatabase db = this.getWritableDatabase();

        ContentValues values = new ContentValues();

        values.put(KEY_NAME, contact.getName());

        values.put(KEY_PH_NO, contact.getPhoneNumber());

        // updating row

        return db.update(TABLE_CONTACTS, values, KEY_ID + " = ?",

                new String[] { String.valueOf(contact.getID()) });

    }

   

    public void deleteContact(Contact contact) {

        SQLiteDatabase db = this.getWritableDatabase();

        db.delete(TABLE_CONTACTS, KEY_ID + " = ?",

                new String[] { String.valueOf(contact.getID()) });

        db.close();

    }

  

    public int getContactsCount() {

        String countQuery = "SELECT  * FROM " + TABLE_CONTACTS;

        SQLiteDatabase db = this.getReadableDatabase();

        Cursor cursor = db.rawQuery(countQuery, null);

        cursor.close();

        // return count

        return cursor.getCount();

    }

}

3) Using the above given code in a MainActivity Class :)

import java.util.List;

import java.util.Vector;

import android.os.Bundle;

import android.app.Activity;

import android.database.Cursor;

import android.database.sqlite.SQLiteDatabase;

import android.database.sqlite.SQLiteException;

import android.util.Log;

import android.view.Menu;

public class MainActivity extends Activity {

Cursor user = null;

DatabaseHandler db = null;

@Override

public void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

db = new DatabaseHandler(this);

/**

* 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);

}

Contact cont = new Contact();

cont.setID(3);

cont.setName("jitesh");

cont.setPhoneNumber("7829955125");

int x = db.updateContact(cont);

Log.d("log for update: ", x + "");

Log.d("log for update: ", checkDataBase());

setContentView(R.layout.activity_main);

}

public void onDestroy() {

super.onDestroy();

db.close();

}

public String checkDataBase() {

SQLiteDatabase checkDB = null;

try {

String myPath = "/data/data/ " YOURS PACKAGE NAME"/contactsManager";

checkDB = SQLiteDatabase.openDatabase(myPath, null,

SQLiteDatabase.OPEN_READONLY

| SQLiteDatabase.NO_LOCALIZED_COLLATORS);

} catch (SQLiteException e) {

// database does't exist yet.

}

if (checkDB != null) {

checkDB.close();

}

return checkDB != null ? "exists" : "not exist";

}

}

Just use the classes and enhance yours code , have a great day with android ahead :)