Guys i came across this code snippet and i have one question

Question

// Is the passed string a number?
public static boolean isNumber(String s) {
if (s.length() == 0) {
return false;
}

char[] chars = s.toCharArray();
for (int i = 0; i < chars.length; i++) {
char c = chars[i];
if (i != 0 && c == '-') { // the string contains a hyphen
return false;
}
if (!Character.isDigit(c) && c != '-') { // not a number and doesn't start with a hyphen
return false;
}
if (i == 0 && c == '-' && chars.length == 1) { // not a hyphen
return false;
}
}
return true;
}
There are 3 if statements after the first if statement.
The method check for a number in a string.
Character.isDigit(c) would suffice for that.
What is the need for the three if statements.
I dont see the need for 3 if statement.
Just Character.isDigit() will do the trick.
Plis tell me am i wrong ??

Answer 1

The number could be negative. In that case, a hyphen ('-') is a valid character in a number which is not a digit (isDigit() would fail). But a hyphen only makes sense under certain conditions. It seems to me, those if's test those conditions.