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  } }}