How to calculate the number of whitespaces in a String

Question

I am trying to remove whitespaces in the beginning of my String by doing the .trim() method. But when I try to calculate how many whitespaces I remove it won't work. I have tried making an equation: int spaces = line.length() - line.trim().length(). But for some reason it always ends up saying the length of the line thats being inputted. Am I missing something here? Or is it some other part of my code?

public Squeeze(FileInput inFile, FileOutput outFile)
{
    int spaces = 0;
    String line = "";
    while(inFile.hasMoreLines())
    {
        line = inFile.readLine();
        line = line.trim();
        spaces = line.length() - line.trim().length();
        outFile.println(spaces + line);

    }
    outFile.close();
}

Answer 1

Note: The OP's code doesn't actually count all whitespaces, only leading ones. For those who want a direct answer to the question:

If you have commons:

int count = StringUtils.countMatches(yourText, " ");

If you don't:

int count = yourText.length() - yourText.replace(" ", "").length();

The following solution is based on the OP's code only.

Your problem is in this part:

line = line.trim();
// At this point, 'line' has already been trimmed.
spaces = line.length() - line.trim().length();

You'll need to either put the trimmed version into some other variable, or move the line = line.trim() line until at least after you've counted the spaces.

public Squeeze(FileInput inFile, FileOutput outFile)
{
int spaces = 0;
String line = "";
String trimmedLine = "";
while(inFile.hasMoreLines())
{
    line = inFile.readLine();
    trimmedLine = line.trim();
    spaces = line.length() - trimmedLine.length();
    outFile.println(Format.left(spaces, 4) + line);

}
outFile.close();
}