java判断用户输入的是否至少含有N位小数的实例

public class ddouble {
 public static void main(String args[]) {
  String str = " .1124 ";
  boolean sfdouble = doubleyn(str,4);
  System.out.println(sfdouble);
 }
 public static boolean doubleyn(String str,int dousize){
  try {
   double num=Double.valueOf(str);//把字符串强制转换为数字
   if(str.trim().indexOf(".") == -1){
    return false;
   }
   int fourplace = str.trim().length() - str.trim().indexOf(".") - 1;
   if(fourplace<dousize){
    return false;
   }else{
    return true;
   }
  } catch (Exception e) {
   return false;//如果抛出异常，返回False
  }
 }
}