TopNRunner.java

package de.lray.intercom.highscore;

import java.io.FileNotFoundException;
import java.io.IOException;

/**
 * Runner class for command line calls.
 *
 * Extracts the given parameter, transforms them to the sub components and shows the result.
 */
public class TopNRunner {

    private static final String RESULT_MESSAGE = "\n\nThe following numbers are the top positions:\n";
    private static final String FILE_NOT_FOUND_MESSAGE = "The file could not be found: ";
    private static final String POSITION_IS_NAN_MESSAGE = "Position parameter is not a number.";
    private static final String PARAMETER_MISSING = "Please use the following parameter: <filename> [<numberOfRanks>]";
    private static final String IO_EXCEPTION_MESSAGE = "IOException occurred:";

    public static void main(String[] args) {

        String fileName = "";
        int numRankings = TopNStrategy.DEFAULT_HIGHSCORE_LENGTH;

        try {
            fileName = args[0];
            if (args.length > 1) {
                numRankings = Integer.valueOf(args[1]);
            }

            FileTraverser importer = FileTraverser.createInstance(
                    fileName,
                    TopNStrategy.createInstance(numRankings),
                    System.out
            );

            Integer[] highScore = importer.traverseWithStrategy();

            System.out.println(RESULT_MESSAGE);
            for (int i:highScore) {
                System.out.println("->"+ i);
            }

        } catch (FileNotFoundException fnfe) {
            System.out.println(FILE_NOT_FOUND_MESSAGE + fileName);
        } catch (IOException ioe) {
            System.out.println(IO_EXCEPTION_MESSAGE + ioe.getMessage() );
        } catch (NumberFormatException nfe) {
            System.out.println(POSITION_IS_NAN_MESSAGE);
        } catch (IndexOutOfBoundsException iobe) {
            System.out.println(PARAMETER_MISSING);
        }

    }
}