Add WhyMethods example code

Author: phrdang

src/com/codefortomorrow/intermediate/chapter11/examples/Methods.java

@@ -2,11 +2,13 @@
 
 public class Methods {
     public static void main(String[] args) {
+        // prints "Hello World" 5 times
         for (int i = 0; i < 5; i++) {
             printMessage();
         }
     }
 
+    /** Prints "Hello World" */
     public static void printMessage() {
         System.out.println("Hello World");
     }

src/com/codefortomorrow/intermediate/chapter11/examples/WhyMethods.java

@@ -0,0 +1,36 @@
+package com.codefortomorrow.intermediate.chapter11.examples;
+
+import java.util.Scanner;
+
+public class WhyMethods {
+    public static void main(String[] args) {
+        // cleaner code because methods group actions
+        printMessages();
+        printSum();
+    }
+
+    /** Prints 3 messages */
+    public static void printMessages() {
+        System.out.println("May the Force be with you");
+        System.out.println("Tahiti, it's a magical place");
+        System.out.println("Live long and prosper");
+    }
+
+    /** Prints the sum of 2 numbers */
+    public static void printSum() {
+        Scanner input = new Scanner(System.in);
+
+        // prompt user to enter 2 numbers
+        System.out.print("Enter number 1: ");
+        double num1 = input.nextDouble();
+        System.out.print("Enter number 2: ");
+        double num2 = input.nextDouble();
+
+        double sum = num1 + num2;
+
+        // print the sum of those numbers
+        System.out.println("Sum: " + sum);
+
+        input.close();
+    }
+}