up to string utils

src/main/java/rocks/zipcode/quiz5/collections/Food.java

@@ -7,9 +7,9 @@ import java.util.*;
 /**
  * @author leon on 27/12/2018.
  */
-public class Food <SpiceType extends Class<? extends Spice>> {
+public class Food  {
 
-    Map<Spice, Integer> spiceCount = new HashMap<>();
+    Map<Spice, Integer> spiceCount = new LinkedHashMap<>();
 
     public List<Spice> getAllSpices() {
         Set<Spice> spicekeys = spiceCount.keySet();
@@ -18,7 +18,7 @@ public class Food <SpiceType extends Class<? extends Spice>> {
         return result;
     }
 
-    public  Map<SpiceType, Integer> getSpiceCount() {
+    public <SpiceType extends Class<? extends Spice>> Map<SpiceType, Integer> getSpiceCount() {
         return null;
     }
 

src/main/java/rocks/zipcode/quiz5/fundamentals/Calculator.java

@@ -1,35 +1,45 @@
 package rocks.zipcode.quiz5.fundamentals;
 
+import java.util.ArrayList;
+
 /**
  * @author leon on 21/12/2018.
  */
 public class Calculator {
     public static Double squareRoot(Double value) {
-        return null;
+        return Math.sqrt(value);
     }
 
     public static Double square(Double value) {
-        return null;
+        return value*value;
     }
 
     public static Double[] squareRoots(Double... value) {
-        return null;
+        ArrayList<Double> result = new ArrayList<>();
+        for (Double dbl : value) {
+            result.add(squareRoot(dbl));
+        }
+        return result.toArray(new Double[0]);
     }
 
     public static Double[] squares(Double... values) {
-        return null;
+        ArrayList<Double> result = new ArrayList<>();
+        for (Double dbl : values) {
+            result.add(square(dbl));
+        }
+        return result.toArray(new Double[0]);
     }
 
     public static Double add(Double value1, Double value2) {
-        return null;
+        return value1 + value2;
     }
 
     public static Double subtract(Double value1, Double value2) {
-        return null;
+        return value1-value2;
     }
 
 
     public static Double divide(Double divisor, Double dividend) {
-        return null;
+        return divisor/dividend;
     }
 }

src/main/java/rocks/zipcode/quiz5/fundamentals/StringUtils.java

@@ -5,30 +5,74 @@ package rocks.zipcode.quiz5.fundamentals;
  */
 public class StringUtils {
     public static Character getMiddleCharacter(String string) {
-        return null;
+        return string.charAt(string.length() / 2);
     }
 
     public static String capitalizeMiddleCharacter(String str) {
-        return null;
+        int midIndex = str.length() / 2;
+        return str.substring(0, midIndex) + str.substring(midIndex, midIndex + 1).toUpperCase() + str.substring(midIndex + 1);
     }
 
     public static String lowerCaseMiddleCharacter(String str) {
-        return null;
+        int midIndex = str.length() / 2;
+        return str.substring(0, midIndex) + str.substring(midIndex, midIndex + 1).toLowerCase() + str.substring(midIndex + 1);
     }
 
     public static Boolean isIsogram(String str) {
-        return null;
+        char[] stringChars = str.toCharArray();
+        for (int i = 0; i < str.length(); i++) {
+            for (int j = 0; j < str.length(); j++) {
+                if (i != j) {
+                    if (stringChars[i] == stringChars[j]) {
+                        return false;
+                    }
+                }
+            }
+        }
+        return true;
     }
 
     public static Boolean hasDuplicateConsecutiveCharacters(String str) {
-        return null;
+        char[] stringChars = str.toCharArray();
+        for (int i = 1; i < str.length(); i++) {
+            if (stringChars[i] == stringChars[i - 1]) {
+                return true;
+            }
+        }
+        return false;
     }
 
     public static String removeConsecutiveDuplicateCharacters(String str) {
-        return null;
+        String result = "";
+        char[] stringChars = str.toCharArray();
+        for (int i = 1; i < str.length(); i++) {
+            if (stringChars[i] == stringChars[i - 1]) {
+                stringChars[i] = ' ';
+                stringChars[i - 1] = ' ';
+            }
+        }
+        for (char letter : stringChars) {
+            if (letter != ' ') {
+                result += letter;
+            }
+        }
+        return result;
     }
 
     public static String invertCasing(String str) {
-        return null;
+        char[] stringChars = str.toCharArray();
+        String result = "";
+        for (int i = 0; i < str.length(); i++) {
+            if (stringChars[i]>96 && stringChars[i]<123) {
+                stringChars[i] = (char) (stringChars[i] - 32);
+            }else if (stringChars[i]>64 && stringChars[i]<91){
+                stringChars[i] = (char) (stringChars[i] + 32);
+            }
+        }
+        for (char letter : stringChars) {
+            result += letter;
+        }
+        return result;
     }
+
 }