Chapter16a.java

/*
    Chater16a.java
    CIS 260
    David Klick
    2016-02-15

This program demonstrates regular expressions used with
    the String.matches method.
*/

import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.FileSystems;
import java.nio.charset.Charset;
import java.util.List;
import java.util.ArrayList;
import java.io.IOException;

public class Chapter16a {
    private static final boolean DISPLAY = true;
    
    private static class SearchPair {
        public String pattern, description;
        public SearchPair(String p, String d) {
            pattern = p;
            description = d;
        }
    }
    
    public static void main(String[] args) {
        int match = 0;
        List<String> lines;
        SearchPair[] search = {
            new SearchPair("a.*", "Starts with \"a\""),
            new SearchPair("aa.*", "Starts with \"aa\""),
            new SearchPair(".*a.*", "Contains an \"a\""),
            new SearchPair(".*aa.*", "Contains an \"aa\""),
            new SearchPair("a.*a", "Starts and ends with an \"a\""),
            new SearchPair(".*a.*a.*a.*", "Contains three \"a\"s"),
            new SearchPair(".*([ai]).*\\1.*\\1.*", "Contains three \"a\"s or \"i\"s"),
            new SearchPair(".*(bob|carol|ted|alice).*", "Contains bob or carol or ted or alice")
        };
        
        try {
            Path path = FileSystems.getDefault().getPath("", "dict.txt");
            lines = Files.readAllLines(path, Charset.defaultCharset());
            for (SearchPair p : search) {
                match = 0;
                String pat = p.pattern;
                System.out.println(p.description);
                for (String line : lines) {
                    if (line.matches(pat)) {
                        if (DISPLAY) System.out.println(line);
                        match++;
                    }
                }
                if (match == 0) System.out.println("No matches found\n");
                else System.out.println(match + " matches found\n");
            }
            
        } catch (IOException e) {
            System.out.println("Error opening or reading input file");
        }
    }
}