JAVA 数组字符串去重

public static void main(String[] args) {
    String str="a,b,c,a,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z";
    System.out.println(deduplication(str));
}

public static String deduplication(String v) {
    if (!StringUtils.isEmpty(v)) {
        String[] arr = v.split(",");
        List<String> list = new ArrayList<>();
        for (int i = 0; i < arr.length; i++) {
            String s = arr[i].trim();
            if (!list.contains(s)) {
                list.add(s);
            }
        }
        StringBuilder sb = new StringBuilder();
        for (String s : list) {
            sb.append(s).append(",");
        }
        if (!StringUtils.isEmpty(sb.toString())) {
            sb.deleteCharAt(sb.length() - 1);
            return sb.toString();
        }
    }
    return v;
}