344 Reverse String/ 345 Reverse Vowel String

resource: http://javahungry.blogspot.com/2014/12/5-ways-to-reverse-string-in-java-with-example.html

2 things to remember:

• StringBuilder class has reverse() built in, while String doesn't.
• String has toCharArray(), while StringBuilder doesnt'

Convert String into Char Array then do other twist:

Method1:

Scan through the char Array from end to beginning.

Method2:

1. Scan through both side simultaneously.
2. Swap the beginning and end.

Method3:

1. Store the value into a LinkedList
2. use Java.Collection.reverse() function

Use StringBuilder reverse() function

345

Store vowel characters:

resource: http://m.blog.csdn.net/article/details?id=51546410

Into hashSet:

ps: The reason use Set instead of array

http://javahungry.blogspot.com/2014/12/5-ways-to-reverse-string-in-java-with-example.html

Just store them all into a string

But need to be taken care by using

String vowels = "aeiouAEIOU";
vowels.contains(String.valueOf(character));

Using stack to pop and push

SMART ASS :D

code:

public String reverseVowels(String s) {

        String vowels = "aeiouAEIOU";
        Stack<String> stack = new Stack<String>();
        char[] array = s.toCharArray();

        for(char ch : array){
            if(vowels.contains(String.valueOf(ch))){
                stack.add(String.valueOf(ch));
            }
        }

        StringBuilder builder = new StringBuilder();

        for(char ch : array)
        {
            if(vowels.contains(String.valueOf(ch))){
                String pop = stack.pop();
                builder.append(pop);
            }
            else{
                builder.append(ch);
            }
        }

        return builder.toString();
    }