StringParser.java

      */
     public static String upperCaseString(String s)
     {
-        return null;
+        return s.toUpperCase();
     }
 
     /**
      * @return String
      */
     public static String lowerCaseString(String s) {
-        return null;
+        return s.toLowerCase();
     }
 
     /**
      * @return String
      */
     public static Character getFirstCharacter(String s) {
-        return null;
+        return s.charAt(0);
     }
 
     /**
      * @return String
      */
     public static Character getNthCharacter(String s, Integer n) {
-        return null;
+        return s.charAt(n);
     }
 
     /**
      * @return String
      */
     public static String upperCaseFirstCharacter(String s) {
-        return null;
+        s = s.substring(0,1).toUpperCase() + s.substring(1);
+        return s;
     }
 
     /**
      * @return String
      */
     public static String camelCaseString(String s) {
-        return null;
+        String[] temp = s.split("\\s+");
+        String fin = "";
+        for(String word : temp){
+            fin += word.substring(0,1).toUpperCase() + word.substring(1).toLowerCase();
+        }
+        return fin;
     }
 
     /**
      * @return String
      */
     public static String snakeCaseString(String s) {
-        return null;
+        String[] temp = s.split("\\s+");
+        String fin = "";
+        for(String word : temp){
+            fin += String.format("%s_",word.toLowerCase());
+        }
+        return fin.substring(0,fin.length()-1);
     }
 
     /**
      * @return String
      */
     public static Integer getLength(String s) {
-        return null;
+        return s.length();
     }
 
     /**
      * @return String
      */
     public static Boolean isEqual(String s1, String s2) {
-        return null;
+        return s1.equals(s2);
     }
 
     /**
      * @return String
      */
     public static Boolean isEqualIgnoreCase(String s1, String s2) {
-        return null;
+        s1 = s1.toLowerCase();
+        s2 = s2.toLowerCase();
+        return s1.equals(s2);
     }
 }