java/TemperatureConverter.java

/**
 * Temperature Converter Program
 * Convert between Celsius and Fahrenheit
 */
public class TemperatureConverter {
    
    /**
     * Convert Celsius to Fahrenheit
     * 
     * @param celsius Celsius temperature
     * @return Fahrenheit temperature
     */
    public static double celsiusToFahrenheit(double celsius) {
        // Formula: Fahrenheit = Celsius * 9/5 + 32
        return celsius * 9.0 / 5.0 + 32.0;
    }
    
    /**
     * Convert Fahrenheit to Celsius
     * 
     * @param fahrenheit Fahrenheit temperature
     * @return Celsius temperature
     */
    public static double fahrenheitToCelsius(double fahrenheit) {
        // Formula: Celsius = (Fahrenheit - 32) * 5/9
        return (fahrenheit - 32.0) * 5.0 / 9.0;
    }
    
    /**
     * Main method - program entry point
     */
    public static void main(String[] args) {
        java.util.Scanner scanner = new java.util.Scanner(System.in);
        
        System.out.print("Please enter temperature and unit (e.g. 36.6 C or 97 F): ");
        String s = scanner.nextLine().trim();
        
        if (s.isEmpty()) {
            System.out.println("Input is empty, program exit.");
            scanner.close();
            return;
        }
        
        String[] parts = s.split(" ");
        
        try {
            double value = Double.parseDouble(parts[0]);
            String unit = (parts.length > 1) ? parts[1].toUpperCase() : "C";
            
            if (unit.startsWith("C")) {
                double f = celsiusToFahrenheit(value);
                System.out.printf("%.2f C = %.2f F%n", value, f);
            } else if (unit.startsWith("F")) {
                double c = fahrenheitToCelsius(value);
                System.out.printf("%.2f F = %.2f C%n", value, c);
            } else {
                System.out.println("Unknown unit, please use C or F.");
            }
            
        } catch (Exception e) {
            System.out.println("Input error, please use format like: 36.6 C");
        } finally {
            scanner.close();
        }
    }
}