Leetcode 65 Valid Number

Validate if a given string is numeric.

Some examples:

"0"

=>

true

" 0.1 "

=>

true

"abc"

=>

false

"1 a"

=>

false

"2e10"

=>

true

public class Solution {
public boolean isNumber(String s) {
s = s.trim();
boolean pointHave = false;
boolean eHave = 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(eHave || pointHave)
{
return false;
}
pointHave = true;
}
else if(s.charAt(i) == 'e')
{
if(eHave || !numberSeen)
{
return false;
}
numberAfterE = false;
eHave = 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;
}
}