A simple Java calculator supports four operations (Summation, Subtraction, Multiplying, and Division) without using if or switch statements. (Using Reflection)

Java Calculator Using Reflection.java

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.Scanner;

public class MainClass {
    public static void main(String[] args) throws ClassNotFoundException, InvocationTargetException, IllegalAccessException, NoSuchMethodException {
        Scanner scanner = new Scanner(System.in);
        Class<?> operations = Class.forName("MainClass");
        MainClass mainClass = new MainClass();
        Method method = operations.getDeclaredMethod(scanner.next(), double.class, double.class);
        System.out.println(method.invoke(mainClass, scanner.nextDouble(), scanner.nextDouble()));
    }

    double sum(double x, double y) {
        return x + y;
    }

    double sub(double x, double y) {
        return x - y;
    }

    double mul(double x, double y) {
        return x * y;
    }

    double div(double x, double y) {
        return x / y;
    }
}