done: main and partial bonus exercises

src/main/java/BonusExercises.java

@@ -20,7 +20,7 @@ public class BonusExercises {
             - Each segment (between dots) must follow same hyphen rules
      */
     public boolean validateEmail(String email) {
-        String regex = ""; // todo
+        String regex = "^(?!.*\\.\\.)[a-zA-Z0-9]([a-zA-Z0-9_.-]*[a-zA-Z0-9])?@[a-zA-Z0-9]([a-zA-Z0-9-]*[a-zA-Z0-9])?(\\.[a-zA-Z0-9]([a-zA-Z0-9-]*[a-zA-Z0-9])?)*$";
         Pattern pattern = Pattern.compile(regex);
         Matcher matcher = pattern.matcher(email);
 
@@ -39,7 +39,14 @@ public class BonusExercises {
         If no match for a date is found in the string, return null.
     */
     public String findDate(String string) {
-        // todo
+//        String regex = "\\b(\\d{4}[/-]\\d{2}[/-]\\d{2}|\\d{2}[/-]\\d{2}[/-]\\d{4})\\b";
+//        Pattern pattern = Pattern.compile(regex);
+//        Matcher matcher = pattern.matcher(string);
+//        if (matcher.find())
+//        {
+//            return matcher.group();
+//        }
+        //Checking day-month compatibility!!!!!!
         return null;
     }
 
@@ -54,8 +61,62 @@ public class BonusExercises {
         - has no white-space in it
      */
     public int findValidPasswords(String string) {
-        // todo
-        return -1;
+        if (string == null) {return 0;}
+        String[] words = string.split("\\s+");
+        int passwordCount = 0;
+        for (String word : words)
+        {
+            String cleanWord = cleanWord(word);
+            if (isValid(cleanWord))
+            {
+                passwordCount++;
+            }
+        }
+        return passwordCount;
+    }
+
+    private String cleanWord(String word) {
+        return word.replaceAll("[^a-zA-Z0-9!@#$%^&*]", "");
+    }
+
+    private boolean isValid(String word)
+    {
+        if (word.length() < 8)
+        {
+            return false;
+        }
+
+        boolean hasUppercase = false;
+        boolean hasLowercase = false;
+        boolean hasSpecial = false;
+        boolean hasNumber = false;
+        String special = "!@#$%^&*";
+
+        for (int i = 0; i < word.length(); i++)
+        {
+            char c = word.charAt(i);
+            if (Character.isUpperCase(c))
+            {
+                hasUppercase = true;
+            }
+            else if (Character.isLowerCase(c))
+            {
+                hasLowercase = true;
+            }
+            else if (Character.isDigit(c))
+            {
+                hasNumber = true;
+            }
+            else if (special.indexOf(c) != -1)
+            {
+                hasSpecial = true;
+            }
+            else
+            {
+                return false;
+            }
+        }
+        return hasNumber && hasLowercase && hasSpecial && hasUppercase;
     }
 
     /*
@@ -66,10 +127,35 @@ public class BonusExercises {
      */
     public List<String> findPalindromes(String string) {
         List<String> list = new ArrayList<>();
-        // todo
+        Pattern pattern = Pattern.compile("[a-zA-Z]+");
+        Matcher matcher = pattern.matcher(string);
+        while (matcher.find())
+        {
+            String word = matcher.group();
+            if (word.length() >= 3) {
+                String lowerWord = word.toLowerCase();
+                if (isPalindrome(lowerWord)) {
+                    list.add(word);
+                }
+            }
+        }
         return list;
     }
 
+    private boolean isPalindrome(String word)
+    {
+        boolean isPalindrome = true;
+        int length = word.length();
+        for (int i = 0; i < length/2; i++)
+        {
+            if (word.charAt(i) != word.charAt(length - i - 1))
+            {
+                isPalindrome = false;
+            }
+        }
+        return isPalindrome;
+    }
+
     public static void main(String[] args) {
         // you can test your code here
     }