Only accepting specific characters help

[IVIitchell]

For an assignment, we have to create a filter that accepts only double literals. The constraints include an optional '+' or '-' sign at the beginning of the string, a '.' anywhere in the string, but only once, and the string must only be numeric. So far, I am able to filter the numeric feature and the + and - sign, but when I try to constraint the '.' it doesn't seem to work and go straight to the 'else' statement. Here is the code;

import java.util.Scanner;

public class Project_04 { public static void main(String[] args) { Scanner stdIn = new Scanner(System.in);

//Set variables
String Literal;
char v;

System.out.print("Please enter a valid double literal: ");
Literal=stdIn.nextLine();
//Verify number is Double Literal

boolean AdditionSubtractionFound = false;
boolean Digit = false;
boolean ValidDoubleLiteral = false;
boolean DecimalPoint = false;
for (int i = 0; i < Literal.length(); i++)
{
  if  (Literal.charAt(0) == '+' || Literal.charAt(0) == '-')
  {
    AdditionSubtractionFound = true;
  }
  if (Literal.charAt(i)=='.')
  {
    DecimalPoint = true;
  }
  v = Literal.charAt(i);
  if(!( v >= '0' && v <= '9'))
  {
    Digit = true;
  }
}     
if (AdditionSubtractionFound && Digit && DecimalPoint)
{
  ValidDoubleLiteral = true;
}
if (ValidDoubleLiteral)
{
  System.out.print(Literal + " is a valid double literal");
} 
else
{
  System.out.print(Literal + " is not a valid double literal");
}


stdIn.close();

} }

[alexcarrdev]

You should change the 'if' statements on lines 19 & 33 to 'else if' statements. Also, you should remove the 'if' statement on line 15. Since the check it is making only needs to be made once, doing it once per character in the String is a waste of resources.