problem in replaceAll function ..... not replace all characters in string

package string;

public class MainString {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        String s  = "This is a string";
        //s.replaceAll("aeiou", "");
        removevowels(s);

    }
public static void removevowels(String s)
{
    String s1 = s.replaceAll("[aeiou](?!\\b)", "");
    //String s1 = s.replaceAll("aeiou", "");
    System.out.println(s1);
}
}