Products

//////////////////// Products List //////////////////////////
//--------------- MainActivity.kt ----------------------

import android.content.Intent
import android.graphics.Color
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import androidx.recyclerview.widget.LinearLayoutManager
import kotlinx.android.synthetic.main.activity_main.*

class MainActivity : AppCompatActivity() {

    val dbHandler: DBHandler = DBHandler(this)

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        addProductsToDB()
        configure()
    }

    override fun onRestart() {
        super.onRestart()
        configure()
    }

    private fun configure() {
        recyclerView.layoutManager = LinearLayoutManager(this)
        recyclerView.adapter = ProductAdapter(this)
        btnAdd.setOnClickListener {
            val intent = Intent(this, AddProductActivity::class.java)
            startActivity(intent)
        }
    }


    private fun addProductsToDB() {
        dbHandler.deleteAll()
        dbHandler.addProduct(Product(0, "table", 5))
        dbHandler.addProduct(Product(1, "Chair", 20))
        dbHandler.addProduct(Product(2, "Tablespoon", 200))
        dbHandler.addProduct((Product(3, "Fork", 230)))
        dbHandler.addProduct(Product(4, "Knife", 180))
    }
}

//----------------------- AddProductActivity.kt ----------------------

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import kotlinx.android.synthetic.main.activity_add_product.*

class AddProductActivity : AppCompatActivity() {

    val dbHandler: DBHandler = DBHandler(this)

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_add_product)
        setPointer()
    }

    private fun setPointer() {
        btnAddProduct.setOnClickListener {
            val p = Product(inputPName.text.toString(), Integer.parseInt(inputPQuantity.text.toString()))
            dbHandler.addProduct(p)
            finish()
        }
    }
}

//----------------------- DBHandler.kt ----------------------

import android.content.ContentValues
import android.content.Context
import android.database.sqlite.SQLiteDatabase
import android.database.sqlite.SQLiteOpenHelper

class DBHandler (context: Context): SQLiteOpenHelper(context, DATABASE_NAME, null, DATABASE_VERSION){

    var context: Context? = null

    init {
        this.context = context
    }

    companion object {
        private val DATABASE_VERSION = 1
        private val DATABASE_NAME = "productDB.db"
        val TABLE_PRODUCTS = "products"

        // Declaring columns name
        val COLUMN_ID = "_id"
        val COLUMN_PRODUCTNAME = "productname"
        val COLUMN_QUANTITY = "quantity"

        val CREATE_PRODUCTS_TABLE = "CREATE TABLE IF NOT EXISTS $TABLE_PRODUCTS ($COLUMN_ID INTEGER PRIMARY KEY, " +
                "$COLUMN_PRODUCTNAME TEXT, $COLUMN_QUANTITY INTEGER)"
        val SELECT_PRODUCT = "SELECT * FROM $TABLE_PRODUCTS"
    }
    override fun onCreate(db: SQLiteDatabase) {
        db.execSQL(CREATE_PRODUCTS_TABLE)
    }

    override fun onUpgrade(db: SQLiteDatabase?, oldVersion: Int, newVersion: Int) {

    }

    fun addProduct(product: Product) {
        val values = ContentValues()
        values.put(COLUMN_PRODUCTNAME, product.productName)
        values.put(COLUMN_QUANTITY, product.quantity)

        val db = this.writableDatabase
        db.insert(TABLE_PRODUCTS, null, values)
        db.close()
    }

    fun findProduct(productName: String): Product? {
        val query = "$SELECT_PRODUCT WHERE $COLUMN_PRODUCTNAME = \"$productName\""
        val db = this.readableDatabase
        val cursor = db.rawQuery(query, null)
        var product: Product? = null

        if(cursor.moveToFirst()) {
            cursor.moveToFirst()
            val id = Integer.parseInt(cursor.getString(0))
            val name = cursor.getString(1)
            val quantity = Integer.parseInt(cursor.getString(2))

            product = Product(id, name, quantity)
            cursor.close()
        }
        db.close()
        return product
    }

    fun getAllProducts(): ArrayList<Product> {
        var products: ArrayList<Product> = ArrayList()
        var cursor = readableDatabase.rawQuery(SELECT_PRODUCT, null)
        if(cursor.moveToFirst()) {
            while(!cursor.isAfterLast) {
                val product = Product(
                    Integer.parseInt(cursor.getString(0)),
                    cursor.getString(1),
                    Integer.parseInt(cursor.getString(2))
                )
                products.add(product)
                cursor.moveToNext()
            }
        }
        cursor.close()
        return products
    }

    fun deleteProduct(productName: String): Boolean {
        var result = false
        val query = "$SELECT_PRODUCT WHERE $COLUMN_PRODUCTNAME = \"$productName\""
        val db = this.writableDatabase
        val cursor = db.rawQuery(query, null)

        if(cursor.moveToFirst()) {
            //cursor.moveToFirst()
            val id = Integer.parseInt(cursor.getString(0))
            db.delete(TABLE_PRODUCTS, "$COLUMN_ID = ?", arrayOf(id.toString()))
            cursor.close()
            result = true
        }
        db.close()
        return result
    }

    fun deleteAll() {
        val db = this.writableDatabase
        var cursor = db.rawQuery(SELECT_PRODUCT, null)
        if(cursor.moveToFirst()) {
            while(!cursor.isAfterLast) {
                val id = Integer.parseInt(cursor.getString(0))
                db.delete(TABLE_PRODUCTS, "$COLUMN_ID = ?", arrayOf(id.toString()))
                cursor.moveToNext()
            }
        }
        cursor.close()
    }
}

//----------------------- Product.kt ----------------------

class Product {
    var id: Int = 0
    var productName: String? = null
    var quantity: Int = 0

    constructor(id: Int, productName: String, quantity: Int) {
        this.id = id
        this.productName = productName
        this.quantity = quantity
    }

    constructor(productName: String, quantity: Int) {
        this.productName = productName
        this.quantity = quantity
    }
}

//----------------------- ProductAdapter.kt ----------------------

import android.content.Context
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.Toast
import androidx.recyclerview.widget.RecyclerView
import kotlinx.android.synthetic.main.product_layout.view.*

class ProductAdapter(private val context: Context): RecyclerView.Adapter<ProductViewHolder>() {

    val dbHandler: DBHandler = DBHandler(context)

    private var productsName = dbHandler.getAllProducts().map { it.productName }
    private var productsAmount = dbHandler.getAllProducts().map { it.quantity.toString() }

    override fun getItemCount(): Int {
        return productsAmount.count()
    }

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ProductViewHolder {
        val layoutInflater = LayoutInflater.from(parent?.context)
        val cellForRow = layoutInflater.inflate(R.layout.product_layout, parent, false)
        return ProductViewHolder(cellForRow)
    }

    override fun onBindViewHolder(holder: ProductViewHolder, position: Int) {
        holder.view.name.text = productsName[position]
        holder.view.amount.text = productsAmount[position]
        holder.view.setOnClickListener {
            val name = productsName[position].toString()
            dbHandler.deleteProduct(name)
            productsName = dbHandler.getAllProducts().map { it.productName }
            productsAmount = dbHandler.getAllProducts().map { it.quantity.toString() }
            notifyDataSetChanged()
        }
    }
}

class ProductViewHolder(val view: View): RecyclerView.ViewHolder(view) { }

//----------------------- activity_main.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="378dp"
        android:layout_height="507dp"
        android:layout_marginTop="70dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <TextView
        android:id="@+id/textView2"
        android:layout_width="227dp"
        android:layout_height="51dp"
        android:text="@string/products"
        android:textAlignment="center"
        android:textAllCaps="true"
        android:textSize="30sp"
        android:textStyle="bold|italic"
        app:layout_constraintBottom_toTopOf="@+id/recyclerView"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <Button
        android:id="@+id/btnAdd"
        android:layout_width="62dp"
        android:layout_height="60dp"
        android:text="@string/add"
        android:textSize="30sp"
        app:layout_constraintBottom_toTopOf="@+id/recyclerView"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toEndOf="@+id/textView2"
        app:layout_constraintTop_toTopOf="parent" />

</androidx.constraintlayout.widget.ConstraintLayout>

//----------------------- activity_add_product.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=".AddProductActivity">

    <TextView
        android:id="@+id/addProductTxt"
        android:layout_width="215dp"
        android:layout_height="47dp"
        android:text="@string/add_product"
        android:textAlignment="center"
        android:textAllCaps="true"
        android:textSize="30sp"
        android:textStyle="bold|italic"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.136" />

    <TextView
        android:id="@+id/titleTxt"
        android:layout_width="118dp"
        android:layout_height="36dp"
        android:text="@string/product_title"
        android:textSize="18sp"
        android:textStyle="bold|italic"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.17"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/addProductTxt"
        app:layout_constraintVertical_bias="0.168" />

    <TextView
        android:id="@+id/quantityTxt"
        android:layout_width="118dp"
        android:layout_height="36dp"
        android:text="@string/quantity"
        android:textSize="18sp"
        android:textStyle="bold|italic"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.17"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/titleTxt"
        app:layout_constraintVertical_bias="0.086" />

    <EditText
        android:id="@+id/inputPName"
        android:layout_width="179dp"
        android:layout_height="42dp"
        android:ems="10"
        android:hint="@string/title"
        android:inputType="textPersonName"
        android:labelFor="@id/titleTxt"
        app:layout_constraintCircle="@id/titleTxt"
        app:layout_constraintCircleAngle="90"
        app:layout_constraintCircleRadius="170dp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toEndOf="@+id/titleTxt"
        app:layout_constraintTop_toBottomOf="@+id/addProductTxt"
        android:autofillHints="Title" />

    <EditText
        android:id="@+id/inputPQuantity"
        android:layout_width="179dp"
        android:layout_height="42dp"
        android:ems="10"
        android:hint="@string/quantity_add"
        android:inputType="textPersonName"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintCircle="@id/quantityTxt"
        app:layout_constraintCircleAngle="90"
        app:layout_constraintCircleRadius="170dp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toEndOf="@+id/quantityTxt"
        app:layout_constraintTop_toBottomOf="@+id/inputPName"
        android:autofillHints="Quantity" />

    <Button
        android:id="@+id/btnAddProduct"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/add_btn"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.498"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/inputPQuantity"
        app:layout_constraintVertical_bias="0.212" />

</androidx.constraintlayout.widget.ConstraintLayout>

//----------------------- product_layout.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="wrap_content">

    <ImageView
        android:id="@+id/imageView"
        android:layout_width="81dp"
        android:layout_height="68dp"
        android:layout_marginTop="8dp"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:srcCompat="@android:drawable/btn_star_big_on" />

    <TextView
        android:id="@+id/name"
        android:layout_width="240dp"
        android:layout_height="34dp"
        android:layout_marginStart="24dp"
        android:layout_marginTop="8dp"
        android:layout_marginEnd="60dp"
        android:text="name"
        android:textSize="24sp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toEndOf="@+id/imageView"
        app:layout_constraintTop_toTopOf="parent" />

    <TextView
        android:id="@+id/amount"
        android:layout_width="240dp"
        android:layout_height="23dp"
        android:layout_marginStart="24dp"
        android:layout_marginTop="11dp"
        android:layout_marginEnd="60dp"
        android:text="amount"
        app:layout_constraintBottom_toBottomOf="@+id/imageView"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toEndOf="@+id/imageView"
        app:layout_constraintTop_toBottomOf="@+id/name" />
</androidx.constraintlayout.widget.ConstraintLayout>

//----------------------- strings.xml ----------------------

<resources>
    <string name="app_name">Products</string>
    <string name="products">Products</string>
    <string name="add">+</string>
    <string name="add_product">Add Product</string>
    <string name="product_title">Product Title:</string>
    <string name="quantity">Quantity:</string>
    <string name="quantity_add">Quantity</string>
    <string name="title">Title</string>
    <string name="add_btn">Add</string>
</resources>

//----------------------- build.gradle (Module:app) ----------------------

implementation 'androidx.recyclerview:recyclerview:1.1.0' //JUST ADD THIS LINE TO THE DEPENDENCIES