Question

I am working on a class assignment this morning and I want to try and solve a problem I have noticed in all of my team mates programs so far; the fact that spaces in an int/float/double cause Java to freak out.

To solve this issue I had a very crazy idea but it does work under certain circumstances. However the problem is that is does not always work and I cannot figure out why. Here is my “main” method:

import java.util.Scanner;    //needed for scanner class

public class Test2
{
  public static void main(String[] args) 
  {

      BugChecking bc = new BugChecking();
      String i;
      double i2 = 0;

      Scanner in = new Scanner(System.in);   

      System.out.println("Please enter a positive integer");

      while (i2 <= 0.0)
      {
             i = in.nextLine();

             i = bc.deleteSpaces(i);  

            //cast back to float
            i2 = Double.parseDouble(i);

            if (i2 <= 0.0)
            {
                System.out.println("Please enter a number greater than 0.");
            }
      }

      in.close();
      System.out.println(i2);       
 }
}

So here is the class, note that I am working with floats but I made it so that it can be used for any type so long as it can be cast to a string:

public class BugChecking
{
    BugChecking()
    {

    }

    public String deleteSpaces(String s)
    {  

        //convert string into a char array
        char[] cArray = s.toCharArray();

        //now use for loop to find and remove spaces
        for (i3 = 0; i3 < cArray.length; i3++)
        {
            if ((Character.isWhitespace(cArray[i3])) && (i3 != cArray.length)) //If current element contains a space remove it via overwrite
            {
                for (i4 = i3; i4 < cArray.length-1;i4++)
                {
                    //move array elements over by one element
                    storage1 = cArray[i4+1];
                    cArray[i4] = storage1;                  
                }
            }
        }

        s = new String(cArray);

        return s; 
    }  

    int i3; //for iteration
    int i4; //for iteration
    char storage1; //for storage
}

Now, the goal is to remove spaces from the array in order to fix the problem stated at the beginning of the post and from what I can tell this code should achieve that and it does, but only when the first character of an input is the space.

For example, if I input ” 2.0332″ the output is “2.0332”.

However if I input “2.03 445 ” the output is “2.03” and the rest gets lost somewhere.

This second example is what I am trying to figure out how to fix.

EDIT:

David’s suggestion below was able to fix the problem. Bypassed sending an int. Send it directly as a string then convert (I always heard this described as casting) to desired variable type. Corrected code put in place above in the Main method.

A little side note, if you plan on using this even though replace is much easier, be sure to add an && check to the if statement in deleteSpaces to make sure that the if statement only executes if you are not on the final array element of cArray. If you pass the last element value via i3 to the next for loop which sets i4 to the value of i3 it will trigger an OutOfBounds error I think since it will only check up to the last element – 1.

Answer 1

If you’d like to get rid of all white spaces inbetween a String use replaceAll(String regex,String replacement) or replace(char oldChar, char newChar):

    String sBefore = "2.03 445 ";

    String sAfter = sBefore.replaceAll("\\s+", "");//replace white space and tabs
    //String sAfter = sBefore.replace(' ', '');//replace white space only
    double i = 0;

    try {
        i = Double.parseDouble(sAfter);//parse to integer
    } catch (NumberFormatException nfe) {
        nfe.printStackTrace();
    }
    System.out.println(i);//2.03445

UPDATE:

Looking at your code snippet the problem might be that you read it directly as a float/int/double (thus entering a whitespace stops the nextFloat()) rather read the input as a String using nextLine(), delete the white spaces then attempt to convert it to the appropriate format.

This seems to work fine for me:

public static void main(String[] args) {

    //bugChecking bc = new bugChecking();
    float i = 0.0f;
    String tmp = "";

    Scanner in = new Scanner(System.in);

    System.out.println("Please enter a positive integer");

    while (true) {

        tmp = in.nextLine();//read line
        tmp = tmp.replaceAll("\\s+", "");//get rid of spaces

        if (tmp.isEmpty()) {//wrong input
            System.err.println("Please enter a number greater than 0.");
        } else {//correct input

            try{//attempt to convert sring to float
            i = new Float(tmp);
            }catch(NumberFormatException nfe) {    
                System.err.println(nfe.getMessage());
            }

            System.out.println(i);
            break;//got correct input halt loop
        }

    }
    in.close();
}

EDIT:

as a side note please start all class names with a capital letter i.e bugChecking class should be BugChecking the same applies for test2 class it should be Test2