Unable to find number of patterns in a string in Java

Question

I have a string in which size of a particular media is given. I want to search size and print it.

sampleString = "Sample text having sample 4.5GB"

Note: string can have number of patterns such that [4.0GB, 4.0MB, 4GB, 70MB]

"GB" or "MB" could be integer or float.

My idea is to search the pattern like above mentioned in a string and then split it with MB or GB whichever is found and then grab the integer or float corresponding to that.

I have started finding patterns but code couldn't work. Below is my code:

public class CheckSize {
    public static void main(String args[]) {
        System.out.println(size("Sample text having sample 4.5GB"));
    }

    private static String size(String mString) {
        Float size = 0f;
        String mbSize = "";
        String gbSize = "";
        boolean found = mString.matches("\\d");

        if (found) {
            return "size available";
        }
        else {
            return "size is not available";
        }
    }
}

Please help.

Answer 1

This problem is probably best handled by using a formal regex matcher. Here is a skeleton code showing you how you might approach it:

String line = "My first thumb drive stored 1.5GB, but second stored 1TB.";
String pattern = "\\b(\\d+(?:\\.\\d+)?)(?:MB|GB|TB)\\b";

Pattern r = Pattern.compile(pattern);
Matcher m = r.matcher(line);

while (m.find()) {
    System.out.println("Found value: " + m.group(1) );
}

Found value: 1.5
Found value: 1

Demo

The basic idea here is that we can iterate over your text multiple times, pausing at each match, to print out the numbers preceding the storage size string.