To random every word by the first and last character in one sentence.

makeRandom.java

private static int[] BASE_CHARS;

static {
    BASE_CHARS = new int[26];
    int a_idx = (int)'a';
    for (int i=0; i<26; i++) {
        BASE_CHARS[i] = a_idx + i;
    }
}

static String makeRandom(String content) {
    if (null == content) {
        throw new Exception("Source content is null!");
    }
    char[] chars = content.toCharArray();
    for (int i=0; i<chars.length; i++) {
        
    }
    return null;
}