Practical No. 14 Design and Develop a Temperature Converter Android Application

Practical No. 14

Design and Develop a Temperature Converter Android Application

Aim

To design and develop an Android Temperature Converter application that converts:

  • Celsius to Fahrenheit

  • Fahrenheit to Celsius

and displays the text:

Student Name: FirstName LastName

on the application screen.

I. Practical Significance

This practical enables students to:

  • Design a user-friendly Android interface using standard UI components.

  • Accept numeric input and apply arithmetic logic.

  • Handle button click events in Android applications.

II. Industry / Employer Expected Outcome(s)

Students will be able to:

  • Design functional converter applications.

  • Implement event-driven logic.

  • Process user input accurately in mobile applications.

III. Course Level Learning Outcome(s)

CO3 – Develop Android applications using UI components and layouts.

IV. Laboratory Learning Outcome(s)

LLO 14.1 – Design and implement a converter application.

V. Relevant Affective Domain Related Outcomes

  • Promotes curiosity and experimentation.

  • Encourages confidence in applying formulas in real applications.

VI. Relevant Theoretical Background

GUI Components

  • TextView – Display labels and results

  • EditText – Accept numeric input

  • Spinner – Select conversion type

  • Button – Trigger conversion

Event Handling

  • setOnClickListener() is used to perform conversion when the button is clicked.

Temperature Conversion Formula

  • Celsius → Fahrenheit
    F = (C × 9/5) + 32

  • Fahrenheit → Celsius
    C = (F − 32) × 5/9

VII. Application File Structure (Tree Diagram)

TemperatureConverter/
├── app/
│   └── src/
│       └── main/
│           ├── java/com/example/temperatureconverter/
│           │   └── MainActivity.java
│           ├── res/
│           │   ├── layout/
│           │   │   └── activity_main.xml
│           │   ├── values/
│           │   │   ├── strings.xml
│           │   │   └── themes.xml
│           └── AndroidManifest.xml
└── build.gradle

VIII. XML Layout Code

File: activity_main.xml

<?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="20dp">

    <TextView
        android:id="@+id/txtStudent"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Student Name: FirstName LastName"
        android:textSize="18sp"
        android:textStyle="bold"
        android:layout_marginBottom="20dp" />

    <EditText
        android:id="@+id/edtInput"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="Enter Temperature"
        android:inputType="numberDecimal" />

    <Spinner
        android:id="@+id/spinnerType"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="10dp" />

    <Button
        android:id="@+id/btnConvert"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Convert"
        android:layout_marginTop="15dp" />

    <TextView
        android:id="@+id/txtResult"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Result:"
        android:textSize="16sp"
        android:layout_marginTop="20dp" />

</LinearLayout>

IX. Java Code

File: MainActivity.java

package com.example.temperatureconverter;

import android.os.Bundle;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Spinner;
import android.widget.TextView;
import android.widget.Toast;

import androidx.appcompat.app.AppCompatActivity;

public class MainActivity extends AppCompatActivity {

    EditText edtInput;
    Spinner spinnerType;
    Button btnConvert;
    TextView txtResult;

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

        edtInput = findViewById(R.id.edtInput);
        spinnerType = findViewById(R.id.spinnerType);
        btnConvert = findViewById(R.id.btnConvert);
        txtResult = findViewById(R.id.txtResult);

        String[] options = {
                "Celsius to Fahrenheit",
                "Fahrenheit to Celsius"
        };

        ArrayAdapter<String> adapter = new ArrayAdapter<>(
                this,
                android.R.layout.simple_spinner_item,
                options
        );
        adapter.setDropDownViewResource(
                android.R.layout.simple_spinner_dropdown_item
        );
        spinnerType.setAdapter(adapter);

        btnConvert.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                if (edtInput.getText().toString().isEmpty()) {
                    Toast.makeText(
                            MainActivity.this,
                            "Please enter temperature",
                            Toast.LENGTH_SHORT
                    ).show();
                    return;
                }

                double input =
                        Double.parseDouble(edtInput.getText().toString());
                String selected =
                        spinnerType.getSelectedItem().toString();
                double result;

                if (selected.equals("Celsius to Fahrenheit")) {
                    result = (input * 9 / 5) + 32;
                    txtResult.setText("Result: " + result + " °F");
                } else {
                    result = (input - 32) * 5 / 9;
                    txtResult.setText("Result: " + result + " °C");
                }
            }
        });
    }
}

X. AndroidManifest.xml (Verified)

<application
    android:allowBackup="true"
    android:label="Temperature Converter"
    android:theme="@style/Theme.Material3.DayNight.NoActionBar">

    <activity android:name=".MainActivity">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>

</application>

XI. Expected Output (UI)







Output Description

  • Student name displayed at the top

  • User enters temperature value

  • Conversion type selected using Spinner

  • Converted result displayed after clicking Convert

XII. Result

Thus, a Temperature Converter Android application was successfully designed and developed using UI components, event handling, and mathematical logic, fulfilling the objectives of Practical.


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