public boolean isNumber(String s) {
s = s.trim();
boolean pointSeen =
false;
boolean eSeen =
false;
boolean numberSeen =
false;
boolean numberAfterE =
true;
for(
int i=
0; i<s.length(); i++) {
if(
'0' <= s.charAt(i) && s.charAt(i) <=
'9') {
numberSeen =
true;
numberAfterE =
true;
}
else if(s.charAt(i) ==
'.') {
if(eSeen || pointSeen) {
return false;
}
pointSeen =
true;
}
else if(s.charAt(i) ==
'e') {
if(eSeen || !numberSeen) {
return false;
}
numberAfterE =
false;
eSeen =
true;
}
else if(s.charAt(i) ==
'-' || s.charAt(i) ==
'+') {
if(i !=
0 && s.charAt(i-
1) !=
'e') {
return false;
}
}
else {
return false;
}
}
return numberSeen && numberAfterE;
}
https://zhuanlan.zhihu.com/p/20042325?columnSlug=simons
