solves reverse vowels of a string

Author: anishLearnsToCode

src/ReverseVowelsOfString.java

@@ -0,0 +1,46 @@
+import java.util.ArrayList;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+
+public class ReverseVowelsOfString {
+    private static final Set<Character> VOWELS = new HashSet<>();
+
+    static {
+        VOWELS.add('a');
+        VOWELS.add('e');
+        VOWELS.add('i');
+        VOWELS.add('o');
+        VOWELS.add('u');
+        VOWELS.add('A');
+        VOWELS.add('E');
+        VOWELS.add('I');
+        VOWELS.add('O');
+        VOWELS.add('U');
+    }
+
+    public static String reverseVowels(String string) {
+        List<Character> vowels = getVowels(string);
+        StringBuilder result = new StringBuilder();
+        for (int index = 0, j = vowels.size() - 1 ; index < string.length() ; index++) {
+            char character = string.charAt(index);
+            result.append(isVowel(character) ? vowels.get(j--) : character);
+        }
+        return result.toString();
+    }
+
+    private static boolean isVowel(char character) {
+        return VOWELS.contains(character);
+    }
+
+    private static List<Character> getVowels(String string) {
+        List<Character> vowels = new ArrayList<>();
+        for (int index = 0 ; index < string.length() ; index++) {
+            char character = string.charAt(index);
+            if (isVowel(character)) {
+                vowels.add(character);
+            }
+        }
+        return vowels;
+    }
+}