Java StringBuffer实现价格的小数点前面每三位用逗号隔开

package ersatz;

import java.io.FileNotFoundException;

public class Ersatz {
  public static void main(String[] args) throws FileNotFoundException {
    String price = "222222222222.2222223333333";
    StringBuffer sb = new StringBuffer(price);
    for (int i = sb.lastIndexOf(".")-3; i > 0; i -= 3) {
      sb.insert(i, ",");
    }
    for (int i = sb.lastIndexOf(".") + 4; i < sb.length(); i += 4) {
      sb.insert(i, ",");
    }
    System.out.println(sb);
  }

}