Working With SQLite In Android Apps

Introduction

Android is one of the most popular operating systems for mobile. You can create the database and manipulate the data in Android apps using SQLite. The database is used to store and retrieve the data. Here, I will show you how to work with SQLite in Android application using Android Studio.

Requirements

• Android Studio
• Little knowledge of XML and Java.
• Android Emulator (or) Android mobile
• Download link (Android Studio)

Steps to be followed

Carefully follow the below steps to work with SQLite Android applications using Android Studio, and I have included the source code below.

Step 1

Open Android Studio and start a new project.



Step 2

Put the application name and company domain. If you wish to use C++ for coding the project, mark the "Include C++ support" checkbox and click Next.



Step 3

Select the Android minimum SDK version. After you chose the minimum SDK, it will show approximate percentage of people using that SDK. Then, click Next.



Step 4

Choose "Basic Activity" and click Next.



Step 5

Put the activity name and layout name. Android Studio basically takes the java class name that you provide as activity name. Click Finish.



Step 6

Go to activity_main.xml and click the text botton. This XML file contains the designing code for Android app. Into the activity_main.xml, copy and paste the below code.

Activity_main.xml code

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
    android:layout_height="match_parent" android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:paddingBottom="@dimen/activity_vertical_margin" tools:context=".MainActivity">

    <EditText
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/user_Input"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="69dp"
        android:width="300dp"
        android:inputType=""
        tools:ignore="LabelFor" />

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/add"
        android:id="@+id/add_Button"
        android:layout_below="@+id/user_Input"
        android:layout_alignStart="@+id/user_Input"
        android:layout_marginTop="40dp"
        android:onClick="addButtonClicked" />

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/delete"
        android:id="@+id/delete_Button"
        android:layout_alignTop="@+id/add_Button"
        android:layout_alignEnd="@+id/user_Input"
        android:onClick="deleteButtonClicked" />

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textAppearance="?android:attr/textAppearanceLarge"
        android:text="Large Text"
        android:id="@+id/records_TextView"
        android:layout_centerVertical="true"
        android:layout_centerHorizontal="true" />
</RelativeLayout>

Step 7

In the MainActivity.java file, copy and paste the below code. Java programming is the back-end language for Android. Do not replace your package name, otherwise the app will not run.

MainActivity.java code

package ganeshannt.sqlite;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;
import android.widget.TextView;

public class MainActivity extends Activity {
// Declare references

    EditText userInput;
    TextView recordsTextView;
    MyDBHandler dbHandler;

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

        userInput = (EditText) findViewById(R.id.user_Input);
        recordsTextView = (TextView) findViewById(R.id.records_TextView);

        dbHandler = new MyDBHandler(this, null, null, 1);
        printDatabase();
    }

    //Print the database
    public void printDatabase(){
        String dbString = dbHandler.databaseToString();
        recordsTextView.setText(dbString);
        userInput.setText("");
    }

    //add your elements onclick methods.
    //Add a product to the database
    public void addButtonClicked(View view){
        // dbHandler.add needs an object parameter.
        Products product = new Products(userInput.getText().toString());
        dbHandler.addProduct(product);
        printDatabase();
    }

    //Delete items
    public void deleteButtonClicked(View view){
        // dbHandler delete needs string to find in the db
        String inputText = userInput.getText().toString();
        dbHandler.deleteProduct(inputText);
        printDatabase();
    }

}

Step 8

Create new MyDBHelper.java file (File ⇒ New ⇒Java class).

In MyDBHelper.java, copy and paste the below code. Java programming contains SQLite query. Do not replace your package name, otherwise the app will not run.

MyDBHelper.java code

package ganeshannt.sqlite;

// This class handles all the database activities
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.database.Cursor;
import android.content.Context;
import android.content.ContentValues;

public class MyDBHandler extends SQLiteOpenHelper{
    private static final int DATABASE_VERSION = 1;
    private static final String DATABASE_NAME = "productDB.db";
    public static final String TABLE_PRODUCTS = "products";
    public static final String COLUMN_ID = "_id";
    public static final String COLUMN_PRODUCTNAME = "productname";

    //We need to pass database information along to superclass
    public MyDBHandler(Context context, String name, SQLiteDatabase.CursorFactory factory, int version) {
        super(context, DATABASE_NAME, factory, DATABASE_VERSION);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        String query = "CREATE TABLE " + TABLE_PRODUCTS + "(" +
                COLUMN_ID + " INTEGER PRIMARY KEY AUTOINCREMENT, " +
                COLUMN_PRODUCTNAME + " TEXT " +
                ");";
        db.execSQL(query);
    }
    //Lesson 51
    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        db.execSQL("DROP TABLE IF EXISTS " + TABLE_PRODUCTS);
        onCreate(db);
    }

    //Add a new row to the database
    public void addProduct(Products product){
        ContentValues values = new ContentValues();
        values.put(COLUMN_PRODUCTNAME, product.get_productname());
        SQLiteDatabase db = getWritableDatabase();
        db.insert(TABLE_PRODUCTS, null, values);
        db.close();
    }

    //Delete a product from the database
    public void deleteProduct(String productName){
        SQLiteDatabase db = getWritableDatabase();
        db.execSQL("DELETE FROM " + TABLE_PRODUCTS + " WHERE " + COLUMN_PRODUCTNAME + "=\"" + productName + "\";");
    }

    // this is goint in record_TextView in the Main activity.
    public String databaseToString(){
        String dbString = "";
        SQLiteDatabase db = getWritableDatabase();
        String query = "SELECT * FROM " + TABLE_PRODUCTS + " WHERE 1";// why not leave out the WHERE  clause?

        //Cursor points to a location in your results
        Cursor recordSet = db.rawQuery(query, null);
        //Move to the first row in your results
        recordSet.moveToFirst();

        //Position after the last row means the end of the results
        while (!recordSet.isAfterLast()) {
            // null could happen if we used our empty constructor
            if (recordSet.getString(recordSet.getColumnIndex("productname")) != null) {
                dbString += recordSet.getString(recordSet.getColumnIndex("productname"));
                dbString += "\n";
            }
            recordSet.moveToNext();
        }
        db.close();
        return dbString;
    }

}

Step 9

Create new Products.java file (File ⇒ New ⇒Java class).

In the Products.java file, copy and paste the below code. Do not replace your package name otherwise app will not run.

Products.java code

package ganeshannt.sqlite;

public class Products {
    private int _id;
    private String _productname;

    //Added this empty constructor in lesson 50 in case we ever want to create the object and assign it later.
    public Products(){

    }
    public Products(String productName) {
        this._productname = productName;
    }

    public int get_id() {
        return _id;
    }

    public void set_id(int _id) {
        this._id = _id;
    }

    public String get_productname() {
        return _productname;
    }

    public void set_productname(String _productname) {
        this._productname = _productname;
    }
}

Step 10

Click the "Make Project" option and run the project.

Deliverables

Here, we have successfully created Text entry application.



Add data




Delete data



Deleted



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Source code

https://github.com/GaneshanNT/sqlite