Computer Science 225
Advanced Programming

Spring 2017, Siena College

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FindInterstates BlueJ Project

Click here to download a BlueJ project for FindInterstates.

FindInterstates Source Code

The Java source code for FindInterstates is below. Click on a file name to download it.

FindInterstates.java

import java.io.File;
import java.io.IOException;
import java.util.Scanner;
import java.util.regex.Pattern;
import java.util.regex.Matcher;

/**
 * Example FindInterstates: look for interstate highway references
 * in a METAL tmg graph file's vertex labels, and report how many are found.
 *
 * @author Jim Teresco, Siena College, Computer Science 225, Spring 2017
 *
 */

public class FindInterstates {

    /**
     * main method to read in a METAL .tmg file as specified in args[0]
     * and print a count of how many vertices in the graph appear to have
     * a reference to an interstate highway
     * 
     * @param args command line parameters, where args[0] is expected
     * to have a filename for a METAL tmg graph file
     */
    public static void main(String[] args) {
        
        if (args.length != 1) {
            System.err.println("Usage: java FindInterstates tmgfile");
            System.exit(1);
        }
    
        // create a Pattern that will match anything with I- followed by 1 or
        // more numbers, with special cases of A (for Alaska interstates), H (for
        // Hawaii interstates), or PR (for Puerto Rico interstates)
        Pattern p = Pattern.compile("I-(A|H|PR)?\\d+");

        int iCount = 0;
        int numV = 0;
        try (Scanner s = new Scanner(new File(args[0]))) {
            
            // first line is version and format info, which we assume is good
            s.nextLine();
            // second line is number of vertices and number of edges in file
            numV = s.nextInt();
            s.nextInt();
            
            for (int v = 0; v < numV; v++) {
                // create a matcher over the vertex label
                Matcher m = p.matcher(s.next());

                if (m.find()) iCount++;
                
                // skip over the lat/lng info that we don't care about here
                s.nextLine();
            }
            
            s.close();
        }
        catch (IOException e) {
            System.err.println(e);
            System.exit(1);
        }
        
        System.out.println("Found " + iCount + " interstate references among " + numV + 
            " vertex labels in " + args[0]);
    }
}