How to develop a mobile application for Android

Introduction

The tutorial will focus on creating a simple Android application using the Java programming language and the Android Studio integrated development environment (IDE).

Prerequisites

To follow this tutorial, you will need:

1. A computer with a recent version of Windows, macOS, or Linux.
2. Java Development Kit (JDK) installed on your computer. You can download it from the Oracle website.
3. Android Studio installed on your computer. You can download it from the Android website.

Creating a new project

Open Android Studio and create a new project. You can do this by selecting "File" -> "New" -> "New Project".

In the dialog that opens, enter a name for your project, select a location on your hard drive to save the project to, and finally select "Empty Activity" as the project template. Click on "Finish" to create the project.

Adding a TextView

A very common element in Android applications is the TextView, which is used to display text to the user. You can add a TextView to your layout like this:

1. Open the activity_main.xml file located in the res/layout directory.
2. Enter the following XML for the TextView:

<TextView
 android:layout_width="wrap_content"
 android:layout_height="wrap_content"
 android:text="Hello, World!"
 android:id="@+id/textView" />

Editing the text of the TextView

Now, we'll add some code to change the text of the TextView when the application starts. To do this, we will edit the MainActivity.java file.

Open the MainActivity.java file and insert the following code:

//Import the TextView class
 import android.widget.TextView;

 public class MainActivity extends AppCompatActivity {
 //This method is called when the app is started
 @Override
 protected void onCreate(Bundle savedInstanceState) {
 super.onCreate(savedInstanceState);
 setContentView(R.layout.activity_main);

 //Get a reference to the TextView
 TextView textView = findViewById(R.id.textView);

 //Set the text of the TextView
 textView.setText("Hello, Android!");
 }
 }

Application testing

You are now ready to test your application. To do this, launch the Android emulator included in Android Studio.

Once the emulator has started, you can click the run button (the green triangle button) in the Android Studio toolbar. This will launch your application in the emulator.

You should see your "Hello, Android!" displayed on the emulator screen.

Conclusion

Congratulations! You've just created and successfully tested your first Android application. From here, you can start further exploring the capabilities of Android Studio and the Android SDK to develop more complex applications.