Weight converter app android source code java

A weight converter app is a practical tool that allows users to convert weights between various units like kilograms, pounds, grams, and ounces. This type of application is ideal for Android development beginners who want to practice Java programming while creating a functional project. This guide explains how to build a weight converter app in Android Studio using Java and covers the design, implementation, and enhancement of the app.

Features of the Weight Converter App

1. User-friendly Interface
   • Allows users to input values conveniently.
   • Displays dropdown menus for selecting source and target units.
2. Accurate Unit Conversion
   • Supports conversions between popular weight units: kilograms, grams, pounds, and ounces.
   • Provides instant results upon calculation.
3. Extensibility
   • Easily adaptable to include additional units or functionalities like history tracking.

Tools and Setup Requirements

• Android Studio: Integrated Development Environment (IDE) for Android development.
• Java Development Kit (JDK): Essential for compiling Java code.
• XML and Java: Used for UI design and backend logic, respectively.
• Dependencies: Android SDK and Gradle for project building.

Step-by-Step Implementation

1. Project Initialization

• Open Android Studio and create a new project.
• Select “Empty Activity” as the template.
• Set the project language to Java.

2. Designing the Layout (XML)

Use the activity_main.xml file to design the interface. Here’s an example:

xmlCopy code<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <EditText
        android:id="@+id/inputWeight"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="Enter Weight" />

    <Spinner
        android:id="@+id/sourceUnit"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@id/inputWeight"
        android:prompt="@string/select_source_unit" />

    <Spinner
        android:id="@+id/targetUnit"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@id/sourceUnit"
        android:prompt="@string/select_target_unit" />

    <Button
        android:id="@+id/convertButton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@id/targetUnit"
        android:text="Convert" />

    <TextView
        android:id="@+id/resultText"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@id/convertButton"
        android:text="Result will appear here" />
</RelativeLayout>

3. Backend Logic (Java)

Implement the conversion logic in MainActivity.java:

javaCopy codepublic class MainActivity extends AppCompatActivity {
    private Spinner sourceUnit, targetUnit;
    private EditText inputWeight;
    private TextView resultText;
    private Button convertButton;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        sourceUnit = findViewById(R.id.sourceUnit);
        targetUnit = findViewById(R.id.targetUnit);
        inputWeight = findViewById(R.id.inputWeight);
        resultText = findViewById(R.id.resultText);
        convertButton = findViewById(R.id.convertButton);

        String[] units = {"Kilograms", "Grams", "Pounds", "Ounces"};
        ArrayAdapter<String> adapter = new ArrayAdapter<>(this, android.R.layout.simple_spinner_item, units);
        sourceUnit.setAdapter(adapter);
        targetUnit.setAdapter(adapter);

        convertButton.setOnClickListener(v -> {
            double value = Double.parseDouble(inputWeight.getText().toString());
            String source = sourceUnit.getSelectedItem().toString();
            String target = targetUnit.getSelectedItem().toString();
            resultText.setText(String.valueOf(convertWeight(value, source, target)));
        });
    }

    private double convertWeight(double value, String source, String target) {
        if (source.equals("Kilograms") && target.equals("Grams")) {
            return value * 1000;
        } else if (source.equals("Grams") && target.equals("Kilograms")) {
            return value / 1000;
        }
        // Add more conversion logic as needed
        return value; // Default: No conversion
    }
}

4. Testing the Application

• Run the app using an Android emulator or a physical device.
• Test various input values and ensure accurate conversions.

Enhancements and Additional Features

• UI Improvements: Add a sleek design using Material Design components.
• Error Handling: Handle invalid inputs gracefully, displaying appropriate error messages.
• History Log: Save past conversions for quick access.
• Multi-Unit Support: Expand to include units for volume, distance, or temperature.
• Dark Mode: Add support for light and dark themes for user convenience.

FAQ

1. Can I use Kotlin instead of Java?
Yes, Kotlin is a modern language for Android development and can be used as an alternative to Java. The logic and structure remain similar.

2. How do I add more units?
You can expand the convertWeight method to include additional cases or use a dictionary-based approach for scalability.

3. What are some alternatives to Android Studio?
Eclipse and IntelliJ IDEA are alternatives, but Android Studio is the recommended IDE for Android development.

4. How can I share the app?
Export the APK from Android Studio and share it directly or upload it to the Google Play Store.

5. Where can I find open-source code for reference?
GitHub repositories like Unit_Converter_App are great resources for exploring similar projects.

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