Project with Classes and Interfaces

Author: dpalmas

Working with Classes and Interfaces in Java/CalcEngine/.idea/.gitignore

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+<?xml version="1.0" encoding="UTF-8"?>
+<module type="JAVA_MODULE" version="4">
+  <component name="NewModuleRootManager" inherit-compiler-output="true">
+    <exclude-output />
+    <content url="file://$MODULE_DIR$">
+      <sourceFolder url="file://$MODULE_DIR$/src" isTestSource="false" />
+    </content>
+    <orderEntry type="inheritedJdk" />
+    <orderEntry type="sourceFolder" forTests="false" />
+  </component>
+</module>

Working with Classes and Interfaces in Java/CalcEngine/.idea/description.html

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+package com.pluralsight.calcengine;
+
+import java.time.LocalDate;
+import java.util.Scanner;
+
+public class Main {
+
+    public static void main(String[] args) {
+        double[] leftVals = {100.0d, 25.0d, 225.0d, 11.0d};
+        double[] rightVals = {50.0d, 92.0d, 17.0d, 3.0d};
+        char[] opCodes = {'a', 's', 'm', 'd'};
+        double[] results = new double[opCodes.length];
+        if (args.length == 0) {
+            for (int i = 0; i < opCodes.length; i++) {
+                results[i] = execute(opCodes[i], leftVals[i], rightVals[i]);
+            }
+            for(double currentResult : results)
+                System.out.println(currentResult);
+        } else if (args.length == 1 && args[0].equals("interactive"))
+            executeInteractively();
+        else if (args.length == 3)
+            handleCommandLine(args);
+        else
+            System.out.println("Please provide an operation code and 2 numeric values");
+    }
+
+    static void executeInteractively() {
+        System.out.println("Enter an operation and two numbers");
+        Scanner scanner = new Scanner(System.in);
+        String userInput = scanner.nextLine();
+        String[] parts = userInput.split(" ");
+        performOperation(parts);
+    }
+
+    private static void performOperation(String[] parts) {
+        char opCode = opCodeFromString(parts[0]);
+        if (opCode == 'w')
+            handleWhen(parts);
+        else {
+            double leftVal = valueFromWord(parts[1]);
+            double rightVal = valueFromWord(parts[2]);
+            double result = execute(opCode, leftVal, rightVal);
+            displayResult(opCode, leftVal, rightVal, result);
+        }
+    }
+
+    private static void handleWhen(String[] parts) {
+        LocalDate startDate = LocalDate.parse(parts[1]);
+        long daysToAdd = (long) valueFromWord(parts[2]);
+        LocalDate newDate = startDate.plusDays(daysToAdd);
+        String output = String.format("%s plus %d days is %s", startDate, daysToAdd, newDate);
+        System.out.println(output);
+    }
+
+    private static void displayResult(char opCode, double leftVal, double rightVal, double result) {
+        char symbol = symbolFromOpCode(opCode);
+//        StringBuilder builder = new StringBuilder(20);
+//        builder.append(leftVal);
+//        builder.append(" ");
+//        builder.append(symbol);
+//        builder.append(" ");
+//        builder.append(rightVal);
+//        builder.append(" = ");
+//        builder.append(result);
+//        String output = builder.toString();
+//        System.out.println(output);
+
+        String output = String.format("%.3f %c %.3f = %.3f", leftVal, symbol, rightVal, result);
+        System.out.println(output);
+    }
+
+    private static char symbolFromOpCode(char opCode) {
+        char[] opCodes = {'a', 's', 'm', 'd'};
+        char[] symbols = {'+', '-', '*', '/'};
+        char symbol = ' ';
+        for (int index = 0; index < opCodes.length; index++) {
+            if (opCode == opCodes[index]) {
+                symbol = symbols[index];
+                break;
+            }
+        }
+        return symbol;
+    }
+
+    private static void handleCommandLine(String[] args) {
+        char opCode = args[0].charAt(0);
+        double leftVal = Double.parseDouble(args[1]);
+        double rightVal = Double.parseDouble(args[2]);
+        double result = execute(opCode, leftVal, rightVal);
+        System.out.println(result);
+    }
+
+    static double execute(char opCode, double leftVal, double rightVal) {
+        double result;
+        switch (opCode) {
+            case 'a':
+                result = leftVal + rightVal;
+                break;
+            case 's':
+                result = leftVal - rightVal;
+                break;
+            case 'm':
+                result = leftVal * rightVal;
+                break;
+            case 'd':
+                result = rightVal != 0 ? leftVal / rightVal : 0.0d;
+                break;
+            default:
+                System.out.println("Invalid opCode: " + opCode);
+                result = 0.0d;
+                break;
+        }
+        return result;
+    }
+
+    static char opCodeFromString(String operationName) {
+        char opCode = operationName.charAt(0);
+        return opCode;
+    }
+
+    static double valueFromWord(String word) {
+        String[] numberWords = {
+                "zero", "one", "two", "three", "four",
+                "five", "six", "seven", "eight", "nine"
+        };
+        double value = -1;
+        for (int index = 0; index < numberWords.length; index++) {
+            if (word.equals(numberWords[index])) {
+                value = index;
+                break;
+            }
+        }
+        if (value == -1d)
+            value = Double.parseDouble(word);
+        return value;
+    }
+}