EXP 9 CALCULATOR APP
AIM
To develop a simple and cute Calculator App in Android Studio using Kotlin, allowing the user
to perform basic arithmetic operations (Addition, Subtraction, Multiplication, Division) with a
mobile-friendly interface and clear input/output validation.
ALGORITHM
1. Start the app.
2. Display two input fields for numbers.
3. Show buttons: ➕ ➖ ✖️ ➗ and (clear).
4. User enters two numbers and taps a button.
5. App checks if both inputs are valid numbers:
o If not: show a toast message “Enter valid numbers”.
o If valid:
▪ Perform the selected operation.
▪ Show the result on the screen.
6. Clear button resets everything.
7. End.
CODE
MainActivity.kt
kotlin CopyEdit
package com.example.calci
import
android.os.Bundle import
android.widget.*
import androidx.appcompat.app.AppCompatActivity
class MainActivity : AppCompatActivity() {
private lateinit var num1: EditText
private lateinit var num2: EditText
private lateinit var result: TextView
private lateinit var addBtn: Button
private lateinit var subBtn: Button
private lateinit var mulBtn: Button
private lateinit var divBtn: Button
private lateinit var clearBtn: Button
override fun onCreate(savedInstanceState:
Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
num1 = findViewById(R.id.number1)
num2 = findViewById(R.id.number2)
result = findViewById(R.id.result)
addBtn = findViewById(R.id.add)
subBtn = findViewById(R.id.subtract)
mulBtn = findViewById(R.id.multiply)
divBtn = findViewById(R.id.divide)
clearBtn = findViewById(R.id.clear)
addBtn.setOnClickListener { calculate("+")
} subBtn.setOnClickListener { calculate("-")
} mulBtn.setOnClickListener { calculate("*")
} divBtn.setOnClickListener { calculate("/")
} clearBtn.setOnClickListener {
num1.text.clear() num2.text.clear()
result.text = ""
}
} private fun calculate(op:
String) { val n1Text =
num1.text.toString() val n2Text =
num2.text.toString()
if (n1Text.isEmpty() || n2Text.isEmpty())
{
Toast.makeText(this, "Enter valid numbers",
Toast.LENGTH_SHORT).show()
return
}
val n1 =
n1Text.toDouble() val n2 =
n2Text.toDouble() val res
= when (op) {
"+" -> n1 + n2
"-" -> n1 - n2
"*" -> n1 * n2
"/" -> {
if (n2 == 0.0) {
Toast.makeText(this, "Cannot divide by zero",
Toast.LENGTH_SHORT).show() return
}
n1 / n2
}
else -> 0.0
}
result.text = "Result: $res"
}
}
activity_main.xml (Cute Styling UI)
xml CopyEdit
<?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:background="#FFF1F8" android:padding="24dp"
android:gravity="center">
<TextView android:text="Cute
Calculator 💖" android:textSize="28sp"
android:textColor="#E91E63"
android:layout_marginBottom="16dp"
android:textStyle="bold"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
<EditText
android:id="@+id/number1"
android:hint="Enter Number 1"
android:inputType="numberDecimal"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:backgroundTint="#E91E63"
android:padding="10dp"
android:layout_marginBottom="12dp"/>
<EditText
android:id="@+id/number2"
android:hint="Enter Number 2"
android:inputType="numberDecimal"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:backgroundTint="#E91E63"
android:padding="10dp"
android:layout_marginBottom="24dp"/>
<LinearLayout
android:orientation="horizontal"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:gravity="center"
android:layout_marginBottom="16dp">
<Button
android:id="@+id/add"
android:text="➕"
android:layout_width="0dp"
android:layout_weight="1"
android:layout_height="wrap_content"
android:backgroundTint="#F8BBD0" />
<Button
android:id="@+id/subtract"
android:text="➖"
android:layout_width="0dp"
android:layout_weight="1"
android:layout_height="wrap_content"
android:backgroundTint="#F8BBD0"
android:layout_marginStart="8dp"/>
<Button
android:id="@+id/multiply"
android:text="✖️"
android:layout_width="0dp"
android:layout_weight="1"
android:layout_height="wrap_content"
android:backgroundTint="#F8BBD0"
android:layout_marginStart="8dp"/>
<Button
android:id="@+id/divide"
android:text="➗"
android:layout_width="0dp"
android:layout_weight="1"
android:layout_height="wrap_content"
android:backgroundTint="#F8BBD0"
android:layout_marginStart="8dp"/>
</LinearLayout>
<Button
android:id="@+id/clear"
android:text=" Clear"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:backgroundTint="#CE93D8"
android:layout_marginBottom="16dp" />
<TextView
android:id="@+id/result"
android:textSize="22sp"
android:textStyle="bold"
android:textColor="#880E4F"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
</LinearLayout>
OUTPUT:
RESULT
Once you run the app:
• You can enter two numbers.
• Tap any operation: ➕ ➖ ✖️ ➗ Result appears below in bold.
• Clear button resets the input.
• If input is missing or invalid, you’ll see a toast message.
