Project Description:
This project involves creating a calculator app for Android devices using XML for layout design and Kotlin for functionality. The goal is to develop an app that is adaptive to different screen sizes, ensuring a consistent user experience across various devices. The design and functionality of the app should closely mirror those of pre-installed calculator apps found on smartphones, emphasizing a user-friendly interface and efficient operation.
- Adaptive layout for various screen sizes and orientations.
- Basic arithmetic operations: addition, subtraction, multiplication, and division.
- Clear and intuitive user interface similar to native calculator apps.
- Error handling for invalid operations.
sudo snap install android-studio --classic
- Download and install the latest version of Android Studio from the Android Developer website.
- Start a new project with the "Empty Activity" template, selecting Kotlin as the programming language.
- /res/ => mkdir layout
- /res/layout => touch activity_main.xml
For an adaptive layout, we'll use ConstraintLayout and LinearLayout for their flexibility and ease of making adaptive UIs. Below is a simplified XML layout to start with. You can enhance it further by looking at the design of the pre-installed calculator app on your device.
<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">
<TextView
android:id="@+id/textViewResult"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginTop="32dp"
android:textSize="32sp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
android:text="0"
android:gravity="end"/>
<!-- Add Buttons for digits and operations here, using a similar approach -->
</androidx.constraintlayout.widget.ConstraintLayout>
For buttons (0-9, +, -, , /, =, etc.), use Button views inside the ConstraintLayout. Arrange them in a grid-like manner by constraining buttons to the sides of other buttons or the parent view. Use android:layout_width and android:layout_height with fixed sizes or wrap_content for buttons, and adjust their app:layout_constraint attributes to position them.
=> check the xml file
More about Android development using xml, check this link:
https://developer.android.com/codelabs/basic-android-kotlin-training-xml-layouts?hl=fr#0
look at the kotlin file
In the kotline file we should just modify in :
class MainActivity : AppCompatActivity()
You should declare all the variables first in the class MainActivity. Just like these example :
there is 3 types of variable that we will use :
-variable for the buttons
-variable for a normal variable :
-variable for the textview:
Just after the declaration of variables, add this function , and we're gonna modify all the things in this function .
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
This is an example how to link a button with the xml , and you should all the rest alone :
nbr_one_button = findViewById(R.id.one)
To link the button with a function , you should use the function :
findViewById(R.id.”name of the id “)
##STEP7 : USEFUL FUNCTION FOR THE RESULT :
THE FUNCTION here , YOU ARE GOING TO USE IT IN BUTTONS WITH NUMBERS
fun writeText(text: CharSequence?) {
val sb = StringBuilder()
sb.append(result.text).append(text)
result.text = sb/toString()
}
- Set up click listeners for the calculator's buttons.
- Implement the logic for performing arithmetic operations.
- Update the display to show results or errors as appropriate.
- Test the app using the Android Emulator for various devices.
- If possible, test on physical devices to ensure compatibility.
- Study existing calculator apps for insights into design and functionality.
- Prioritize UI/UX design to make the app intuitive and easy to use.
Now it is on you to make all these ideas in the correct form . And if you need anything visit the following website :
https://developer.android.com/get-started/overview