Valid Number

题目：

Validate if a given string is numeric

Some examples:
"0" > true
"0.1" >true
"abc" > false

解答：

public boolean isNumber(String s) {
    int i = 0;
    int n = s.length();

    // 略过s前面的空格
    while(i < n && Character.isWhitespace(s.charAt(i))) {
        i++;
    }

    boolean isNumeric = false;

    while(i < n && Character.isDigit(s.charAt(i))) {
        i++;
        isNumeric = true;
    }

    if(i < n && s.charAt(i) == '.') {
        i++;
        while(i < n && Character.isDigit(s.charAt(i))) {
            i++;
            isNumeric = true;
        }
    }

    // 略过s后面的空格
    while(i < n && Character.isWhitespace(s.charAt(i))) {
        i++;
    }

    return isNumerics && i == n;
}