Dank Java Calculator

package com.mattparks.calculator;

import java.util.*;

/**
 * A class that takes inputs from the console and runs calculations.
 */
public class Calculator {
    private Scanner scanner;

    /**
     * Creates a new calculator.
     */
    public Calculator() {
        scanner = new Scanner(System.in);
    }

    /**
     * Runs the inputs and calculations.
     */
    public void run() {
        // Gets the first value.
        System.out.println("Please enter the first number:");
        double a = scanner.nextDouble();

        // Gets the second value.
        System.out.println("Please enter the second number:");
        double b = scanner.nextDouble();

        // Gets the operation.
        System.out.println("Please enter the operation type:");
        String type = scanner.nextLine();
        if (type.isEmpty()) {
            type = scanner.nextLine();
        }

        // Gets the enum and operation interface,
        Operations operations = getOperation(type);

        if (operations == null) {
            System.out.println("Could not find a operation for " + type);
            System.exit(-1);
        }

        // Runs the calculations and displays results.
        Operation operation = operations.operation;
        double result = operation.calculate(a, b);
        System.out.println(a + " " + operations.shortType + " " + b + " = " + result);
    }

    /**
     * A munch of mathematical operations.
     */
    @SuppressWarnings("unused")
    private enum Operations {
        ADDITION((a, b) -> a + b, "+"), SUBTRACTION((a, b) -> a - b, "-"),
        MULTIPLICATION((a, b) -> a * b, "*"), DIVISION((a, b) -> a / b, "/"),
        POWER((a, b) -> Math.pow(a, b), "^");

        public final Operation operation;
        public final String shortType;

        Operations(Operation operation, String shortType) {
            this.operation = operation;
            this.shortType = shortType;
        }
    }

    /**
     * Gets the operations from a short name.
     *
     * @param shortType The short name.
     *
     * @return The operations found with the short name.
     */
    private static Operations getOperation(String shortType) {
        for (Operations o : Operations.values()) {
            if (o.shortType.equals(shortType)) {
                return o;
            }
        }

        return null;
    }

    /**
     * A interface used to define mathematical operations.
     */
    private interface Operation {
        /**
         * Runs a calculation between two inputs.
         *
         * @param a The first value.
         * @param b The second value.
         *
         * @return The resulting value.
         */
        double calculate(double a, double b);
    }
}