JAVA格式化数字字符串，如手机号，银行卡号的格式化

 格式化手机号码为3 3 5

String mobile = "13123456789";
String regex = "(\\d{3})(\\d{3})(\\d{5})";
String formatedMobile = mobile.replaceAll(regex, "$1 $2 $3");
System.out.println(formatedMobile);
// 131 234 56789

格式化银行卡号为4 4 4 剩余

String bankCard = "6225880112345678";
String regex = "(\\d{4})(\\d{4})(\\d{4})(\\d{1})";
String formatedBankCard = bankCard.replaceAll(regex, "$1 $2 $3 $4");
System.out.println(formatedBankCard);
// 6225 8801 1234 5678