CoderByte challenge Letter Change in java

coderbyte_letterChanges.java

import java.util.*; 
import java.io.*;

class Main {  
  public static String LetterChanges(String str) { 
    char[] chars = str.toCharArray();
    for (int i = 0; i < chars.length; i++) {
        if (Character.isLetter(chars[i]))
            if (('a' <= chars[i] && chars[i] < 'z') || ('A' <= chars[i] && chars[i] < 'Z'))
                chars[i] = (char)(chars[i] + 1);
            else
                chars[i] = (char)(chars[i] - 25);
        switch (chars[i]) {
            case 'a':
            case 'e':
            case 'i':
            case 'o':
            case 'u':
                chars[i] = (char)(chars[i] - 32);
        }
    }
    return new String(chars);
  } 
  
  public static void main (String[] args) {  
    // keep this function call here     
    Scanner s = new Scanner(System.in);
    System.out.print(LetterChanges(s.nextLine())); 
  }   
  
}