Most of StringUtils

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

@@ -1,34 +1,112 @@
 package rocks.zipcode.quiz5.fundamentals;
 
+import java.util.HashMap;
+import java.util.Map;
+
 /**
  * @author leon on 21/12/2018.
  */
 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;
+
+        String s = str.valueOf(str.charAt(str.length()/2)).toUpperCase();
+
+        return str.substring(0, str.length()/2) + s + str.substring(str.length()/2 + 1);
     }
 
     public static String lowerCaseMiddleCharacter(String str) {
-        return null;
+
+        String s = str.valueOf(str.charAt(str.length()/2)).toLowerCase();
+
+        return str.substring(0, str.length()/2) + s + str.substring(str.length()/2 + 1);
     }
 
     public static Boolean isIsogram(String str) {
-        return null;
+        Map<Character, Integer> map = new HashMap<>();
+
+        char[] ch = str.toCharArray();
+
+        for(char c : ch){
+            if (!map.containsKey(c)){
+                map.put(c, 1);
+            } else {
+                int count = map.get(c);
+                count++;
+                map.put(c, count);
+            }
+        }
+
+        if (map.size() == 1) {return false;}
+
+        Integer test = map.get(ch[0]);
+
+        for (char key : map.keySet()){
+            System.out.println(key);
+            if (map.get(key) != test){
+                return false;
+            }
+        }
+
+        return true;
     }
 
     public static Boolean hasDuplicateConsecutiveCharacters(String str) {
-        return null;
+
+        for (int i = 1; i < str.length(); i++) {
+            if (str.charAt(i) == str.charAt(i - 1)){
+                return true;
+            }
+
+        }
+        return false;
     }
 
     public static String removeConsecutiveDuplicateCharacters(String str) {
-        return null;
+
+        char[] chArr = str.toCharArray();
+        StringBuilder builder = new StringBuilder();
+        char mark = chArr[0];
+        builder.append(mark);
+
+        for (int i = 1; i < chArr.length; i++) {
+
+            if (chArr[i] == chArr[i - 1]){
+
+            } else {
+                builder.append(chArr[i]);
+            }
+
+
+        }
+
+        return builder.toString();
     }
 
     public static String invertCasing(String str) {
-        return null;
+
+        char[] chArr = str.toCharArray();
+        StringBuilder builder = new StringBuilder();
+
+        for (char c : chArr){
+            if (Character.toString(c).matches("[a-z]")) {
+                builder.append(Character.toString(c).toUpperCase());
+            } else if (Character.toString(c).matches("[A-Z]")){
+                builder.append(Character.toString(c).toLowerCase());
+            } else {
+                builder.append(Character.toString(c));
+            }
+        }
+
+
+
+
+        return builder.toString();
     }
+
+
 }