Thread: Trying to trim and get length then parse from string into Double

I have been trying to trim the and get the length and parse the string into a double from what the user entered to no avail. Any help would be much appreciated. Please bear with me as I am still very new to Java.

So far what Ive done is asked the user to enter up to ten grades, I then added in there, if the user presses enter, then they are done entering. Then I would add up the grades and average them up and print it. I haven't added that coding in there yet, as I am still trying to trim, get length and parse the string into a double.

I know, It would make sense to read doubles from the user, but my instructor specifically asked that we read strings then convert to doubles if and only if the user entered a length > 0 of which I already established into my code.

So I am having troubles trying to trim, get length then parsing into doubles, if you could help me with that, that would be great!

import java.util.*;
import java.io.*;
public class Grades {
 
	public static void main(String[] args)throws IOException {
 
   	   double validGrades = 0;
	   double d = 0;
		double total = 0;
		final int SIZE = 10;
		boolean exit = false;
		int count = 0;
		String gradesEntered;
 
		BufferedReader bf = new BufferedReader(new InputStreamReader(System.in));
		String[ ] grades = new String[SIZE];
		String[ ] trimmedGradesEntered = new String[grades.length];
 
		System.out.println("Please enter up to 10 grades and press enter to finish.");
 
 
		while((count < SIZE) && (exit == false)){
			System.out.print("Grade " + (++count) + ": ");
			gradesEntered = bf.readLine( ) ;
			if(gradesEntered.length() < 1){
				exit = true;
 
			}
		}
 
	}
}

Take a look at :
String (Java Platform SE 6)
and
Double (Java 2 Platform SE v1.4.2)

Here's an small example

   try{
	   String grade = bf.readLine().trim();
	   double gradeDouble = Double.parseDouble(grade);
	}catch(NumberFormatException exF){
		//Handle an incorrect string
	}

BTW I think that's not a collection and generics issue