Thread: Need help with nesting if statements! (Scrub) EDITED

So im doing an assignment with the following requirements:

The program prompts the user to enter a valid three digit
double literal, and checks to make sure the input works.

Requirements:
1. Consists of exactly three of the following characters: +, -, . (decimal point), and 0 through 9.
2. The + or - character may only appear (once) as the first character.
3. The . (decimal point) character must appear exactly once,as either the first, second, or third character.
4. All other characters must be the 0 through 9 characters

EDIT:

Heres what i currently have.

public class Project04 
{
 
	public static void main(String[] args) 
	{
		Scanner stdIn = new Scanner(System.in);
 
		char char0;
		char char1;
		char char2;
		String DL; //Double Literal
 
		System.out.println("Please enter a valid (3 character) double literal :");
		DL = stdIn.nextLine();
 
		char0 = DL.charAt(0);
		char1 = DL.charAt(1);
		char2 = DL.charAt(2);
 
		if (char0 == '+' || char0 == '-')
		{
			if (char1 == '.');
			{
				if ('0' <= char2 && char2 <= '9')
				{
					System.out.println(DL + " Is a valid 3 character double literal");
				}
			}
 
		}
		else if ('0' <= char1 && char1 <= '9');
		{
			if (char2 == '.');
			{
				System.out.println( DL + " Is a valid 3 character double literal");
			}
		}
		if (char0 == '.');
		{
			if ('0' <= char1 && char1 <= '9');
			{
				if ('0' <= char2 && char2 <= '9');
				{
					System.out.println(DL + " Is a valid 3 character double literal");
				}
			}
 
		}
 
 
 
 
 
	}	
 
}

The problem im having is that the code is not checking everything properly. To my understanding the first IF should be checking for a + or -, then if it has a decimal, then if the last char is between 0 and 9, the ELSE checking essentially the same thing except the last 2 chars are switched.The second IF should be checking if the first char is a decimal, and if it is it checks if the next 2 chars are between 0-9.

However, when i run my program, i can type in even "..." and it still says " ... is a valid 3 character double literal.

Do i have to nest these two IF trees together?

I edited the first post

Sorry, in my actual code i do have the requirements listed but i only listed what i thought was the important section of code, since i already gave the requirements in the thread.

To answer your question, +,-, . , and 0-9 are all valid as char0, but + and - are not valid for char1 or char2.

From the looks of it you were very close.

There are multiple ways you could go at this:

• Your way, test the individual chars of the string literal for certain situations
  
  or
  
  
• See if the string contains any character outside the allowed characters, then check to see if it has a decimal (since they all must), see if it has a + or - sign and if so, check that it's at the front. If it fails any of those tests return not a valid string, if it passes there you have it.

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