Validate if a given string is numeric.

Some examples:
"0"=>true
" 0.1 "=>true
"abc"=>false
"1 a"=>false
"2e10"=>true

Note: It is intended for the problem statement to be ambiguous. You should gather all requirements up front before implementing one.

public class Solution {
    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(s.charAt(i)>='0' && 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;
    }
}