how to get a number from a file-CodePudding

I have to get a number from a file, some files have letters and numbers convined. like (dsh8kuebw9) or have spaces like(8 8) how can I get those numbers? I have tried so many times. I have a method to find the occurences of a digit is in a number is the count8 method.

The parseInt converts the line of the file in a integer but because in some files there are letters I am having trouble with my method because it only accepts integers no Strings

File file_a = new File("C:\\name\\textFile8a.txt");
try 
{
    
    FileReader in = new FileReader(file_a);
    BufferedReader readFile = new BufferedReader(in);
    String n = readFile.readLine();
    int num = Integer.parseInt(n);
                
    
    System.out.println(count8(num, 8));
}
catch(IOException e)
{
    System.out.println("file could not be founded");
    System.err.println("OIException: "   e.getMessage());
}

CodePudding user response：

You can remove all the numbers in your string before you parse it by replacing non-numberic characters with an empty string:

String n = readFile.readLine();
n = n.replaceAll("[^0-9]", "");
int num = Integer.parseInt(n);

CodePudding user response：

basic and simple solution

public static ArrayList<Integer> extractNumber(String s) {

        ArrayList returnList = new ArrayList<Integer>();

        Pattern regex = Pattern.compile("\\d[\\d.]*");
        Matcher matcher = regex.matcher(s);
        while (matcher.find()) {
            returnList.add(matcher.group());
        }

        return returnList;
    }

    public static void main(String[] args) {

        File file_a = new File("C:\\name\\textFile8a.txt");
        try {

            FileReader in = new FileReader(file_a);
            BufferedReader readFile = new BufferedReader(in);
            String n = readFile.readLine();
            ArrayList<Integer> numberList = extractNumber(n);
            System.out.println(numberList);

        } catch (IOException e) {
            System.out.println("file could not be founded");
            System.err.println("OIException: "   e.getMessage());
        }
    }