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VNSGU BCA Sem 3: Mobile App Dev (305-2) Practical Solutions - April 2025 Set B

Paper Information

Attribute	Value
Subject	Mobile Application Development - I
Subject Code	305-2
Set	B
Semester	3
Month/Year	April 2025
Max Marks	25
Paper	View Paper | Download PDF

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Questions & Solutions

Q1: Coffee Shop Order App

Max Marks: 20

Create an android app interface to make Order in Coffee Shop. Include Following Modules in app: Home Screen: It Contain List of item of Coffee Shop Payment Screen: Click on Button which moves to Payment Screen from where take input of Card No, CSV No, Card Holder Name and Pin. Display Toast message of Successful On "Payment" Button Click.

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1. Concept Explanation

Multi-Screen Navigation using Intents

An Intent in Android is a messaging object used to request an action from another app component. We use an Explicit Intent to start a secondary Activity (PaymentActivity) from our primary Activity (MainActivity) and pass selected order data using intent.putExtra().

Handling Checkboxes & Selections

We will use Checkboxes for selecting coffee items. This allows students to check multiple items, compile them into a list, and calculate a total price before proceeding to checkout.

Input Validation

Before finalizing payment, the input fields must be validated:

• Card Number (must not be blank and must be 16 digits).
• CVV (must be 3 digits).
• Card Holder Name (must not be empty).
• PIN (must be 4 digits).

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2. Algorithm & Step-by-Step Logic

1. Home Screen (MainActivity):
   • Design a layout with three or four checkboxes (e.g., Espresso, Cappuccino, Latte).
   • Add a "Proceed to Payment" Button.
   • In Kotlin, detect which checkboxes are checked. Collect the selected items and total amount.
   • Use an Intent to transition to PaymentActivity, appending the order details.
2. Payment Screen (PaymentActivity):
   • Design input fields (EditText) for Card Number, Card Holder Name, CVV (numeric), and PIN (numeric password type).
   • Add a "Pay Now" Button.
   • Validate that fields are not empty and meet basic criteria (e.g. CVV length == 3).
   • If valid, show a Toast.makeText(...) with the message "Payment Successful! Order Placed."

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3. Implementation Code & Output

View Solution & Output

Layout File: res/layout/activity_main.xml (Home Screen)

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:padding="24dp"
    android:background="#FAF6F0">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="VD Coffee Corner"
        android:textSize="28sp"
        android:textStyle="bold"
        android:textColor="#4E3629"
        android:layout_gravity="center"
        android:layout_marginBottom="32dp" />

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Select your Coffee:"
        android:textSize="18sp"
        android:textColor="#5D4037"
        android:layout_marginBottom="16dp" />

    <!-- Coffee Checkboxes -->
    <CheckBox
        android:id="@+id/chkEspresso"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Espresso - Rs. 120"
        android:textSize="16sp"
        android:layout_marginBottom="8dp" />

    <CheckBox
        android:id="@+id/chkCappuccino"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Cappuccino - Rs. 150"
        android:textSize="16sp"
        android:layout_marginBottom="8dp" />

    <CheckBox
        android:id="@+id/chkLatte"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Caffè Latte - Rs. 180"
        android:textSize="16sp"
        android:layout_marginBottom="32dp" />

    <!-- Order Button -->
    <Button
        android:id="@+id/btnOrder"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Proceed to Payment"
        android:backgroundTint="#4E3629"
        android:textColor="#FFFFFF"
        android:padding="12dp"
        android:textSize="16sp" />

</LinearLayout>

Kotlin File: MainActivity.kt (Home Screen)

package com.example.coffeeshop

import android.content.Intent
import android.os.Bundle
import android.widget.Button
import android.widget.CheckBox
import android.widget.Toast
import androidx.appcompat.app.AppCompatActivity

class MainActivity : AppCompatActivity() {

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

        val chkEspresso: CheckBox = findViewById(R.id.chkEspresso)
        val chkCappuccino: CheckBox = findViewById(R.id.chkCappuccino)
        val chkLatte: CheckBox = findViewById(R.id.chkLatte)
        val btnOrder: Button = findViewById(R.id.btnOrder)

        btnOrder.setOnClickListener {
            var totalBill = 0
            val orderList = ArrayList<String>()

            if (chkEspresso.isChecked) {
                totalBill += 120
                orderList.add("Espresso")
            }
            if (chkCappuccino.isChecked) {
                totalBill += 150
                orderList.add("Cappuccino")
            }
            if (chkLatte.isChecked) {
                totalBill += 180
                orderList.add("Latte")
            }

            if (orderList.isEmpty()) {
                Toast.makeText(this, "Please select at least one item", Toast.LENGTH_SHORT).show()
            } else {
                // Navigate to Payment Screen and pass data
                val intent = Intent(this, PaymentActivity::class.java).apply {
                    putExtra("BILL_AMOUNT", totalBill)
                    putStringArrayListExtra("ORDER_ITEMS", orderList)
                }
                startActivity(intent)
            }
        }
    }
}

Layout File: res/layout/activity_payment.xml (Payment Screen)

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:padding="24dp"
    android:background="#FAF6F0">

    <TextView
        android:id="@+id/txtOrderSummary"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Order Total: Rs. 0"
        android:textSize="20sp"
        android:textStyle="bold"
        android:textColor="#4E3629"
        android:layout_marginBottom="24dp" />

    <!-- Card Number Input -->
    <EditText
        android:id="@+id/edtCardNumber"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="Card Number (16 Digits)"
        android:inputType="number"
        android:layout_marginBottom="12dp" />

    <!-- Card Holder Name Input -->
    <EditText
        android:id="@+id/edtCardHolder"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="Card Holder Name"
        android:inputType="textPersonName"
        android:layout_marginBottom="12dp" />

    <!-- Row for CVV & PIN -->
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        android:layout_marginBottom="32dp">

        <EditText
            android:id="@+id/edtCvv"
            android:layout_width="0dp"
            android:layout_weight="1"
            android:layout_height="wrap_content"
            android:hint="CVV"
            android:maxLength="3"
            android:inputType="numberPassword"
            android:layout_marginRight="8dp" />

        <EditText
            android:id="@+id/edtPin"
            android:layout_width="0dp"
            android:layout_weight="1"
            android:layout_height="wrap_content"
            android:hint="PIN"
            android:maxLength="4"
            android:inputType="numberPassword"
            android:layout_marginLeft="8dp" />
    </LinearLayout>

    <!-- Pay Button -->
    <Button
        android:id="@+id/btnPay"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Pay &amp; Place Order"
        android:backgroundTint="#4E3629"
        android:textColor="#FFFFFF"
        android:padding="12dp"
        android:textSize="16sp" />

</LinearLayout>

Kotlin File: PaymentActivity.kt (Payment Screen)

package com.example.coffeeshop

import android.os.Bundle
import android.widget.Button
import android.widget.EditText
import android.widget.TextView
import android.widget.Toast
import androidx.appcompat.app.AppCompatActivity

class PaymentActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_payment)

        // Retrieve passed parameters
        val billAmount = intent.getIntExtra("BILL_AMOUNT", 0)
        
        val txtSummary: TextView = findViewById(R.id.txtOrderSummary)
        txtSummary.text = "Order Total: Rs. $billAmount"

        val edtCardNumber: EditText = findViewById(R.id.edtCardNumber)
        val edtCardHolder: EditText = findViewById(R.id.edtCardHolder)
        val edtCvv: EditText = findViewById(R.id.edtCvv)
        val edtPin: EditText = findViewById(R.id.edtPin)
        val btnPay: Button = findViewById(R.id.btnPay)

        btnPay.setOnClickListener {
            val cardNo = edtCardNumber.text.toString().trim()
            val cardHolder = edtCardHolder.text.toString().trim()
            val cvv = edtCvv.text.toString().trim()
            val pin = edtPin.text.toString().trim()

            // 1. Check for blank fields
            if (cardNo.isEmpty() || cardHolder.isEmpty() || cvv.isEmpty() || pin.isEmpty()) {
                Toast.makeText(this, "Please fill in all card details", Toast.LENGTH_LONG).show()
                return@setOnClickListener
            }

            // 2. Validate Card Number Length
            if (cardNo.length != 16) {
                edtCardNumber.error = "Card number must be 16 digits"
                return@setOnClickListener
            }

            // 3. Validate CVV Length
            if (cvv.length != 3) {
                edtCvv.error = "CVV must be 3 digits"
                return@setOnClickListener
            }

            // 4. Validate PIN Length
            if (pin.length != 4) {
                edtPin.error = "PIN must be 4 digits"
                return@setOnClickListener
            }

            // 5. Success Action
            Toast.makeText(this, "Payment Successful!", Toast.LENGTH_LONG).show()
            
            // Finish activities and return
            finish()
        }
    }
}

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💡 Common Examination Mistakes & Tips

Key Pitfalls to Avoid

1. Activity Registration: Any secondary Activity (PaymentActivity) must be declared inside the AndroidManifest.xml under the <application> element. Forgetting this registration is the most common cause of ActivityNotFoundException crashes.
2. Sensitive Data inputs: Input types for CVV and PIN must be set to numberPassword inside the layout XML. Showing plain text values for credentials will result in lost marks for security design.
3. Invalid Intent Keys: Check that the key names used in intent.putExtra("KEY", value) exactly match the string used in intent.getIntExtra("KEY", default) in the secondary activity.