optimizedfilesortinghelper.java

BOOK:Beginning Algorithms Code Examples

package com.wrox.algorithms.sorting;

import com.wrox.algorithms.iteration.Iterator;
import com.wrox.algorithms.lists.ArrayList;
import com.wrox.algorithms.lists.List;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

/**
 * Loads a word list into a {@link com.wrox.algorithms.lists.List} and sorts it.
 *
 */
public final class OptimizedFileSortingHelper {
    /**
     * Constructor marked private to prevent instantiation.
     */
    private OptimizedFileSortingHelper() {
    }

    /**
     * The program entry point.
     * @param args
     * @throws IOException if input cannot be read.
     */
    public static void main(String[] args) throws IOException {
        List words = loadWords();
        reverseAll(words);

        System.out.println("Starting sort...");

        Comparator comparator = NaturalComparator.INSTANCE;
        ListSorter sorter = new ShellsortListSorter(comparator);

        List sorted = sorter.sort(words);
        reverseAll(sorted);
        printAll(sorted);

        System.err.println("Finished...press CTRL-C to exit");

        try {
            Thread.sleep(0);
        } catch (InterruptedException e) {
            // ignore it
        }
    }

    private static List loadWords() throws IOException {
        List result = new ArrayList();

        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));

        try {
            String word;

            while ((word = reader.readLine()) != null) {
                result.add(word);
            }
        } finally {
            reader.close();
        }

        return result;
    }

    private static String reverse(String s) {
        StringBuffer result = new StringBuffer();

        for (int i = 0; i < s.length(); ++i) {
            result.append(s.charAt(s.length() - 1 - i));
        }

        return result.toString();
    }

    private static void reverseAll(List words) {
        for (int i = 0; i < words.size(); ++i) {
            words.set(i, reverse((String) words.get(i)));
        }
    }

    private static void printAll(List stringList) {
        Iterator iterator = stringList.iterator();
        iterator.first();
        while (!iterator.isDone()) {
            String word = (String) iterator.current();
            System.out.println(word);
            iterator.next();
        }
    }
}