sort

/*
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 * and open the template in the editor.
 */
package test;

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.Date;
import java.util.logging.Level;
import java.util.logging.Logger;

/**
 *
 * @author kajacx
 */
public class SortMe {

    private static final SimpleDateFormat sdf = new SimpleDateFormat("YYYY");
    private final ArrayList<Entry> entries;

    private SortMe() {
        this.entries = new ArrayList<>();
    }

    public static void main(String[] args) {
        SortMe sm = new SortMe();
        sm.addMany(20);
        sm.print();

        sm.sort(new NameComparator());
        sm.print();

        sm.sort(new DateComparator());
        sm.print();

        sm.sort(new NumberComparator());
        sm.print();
    }

    private void print() {
        for(Entry e: entries) {
            System.out.println(e);
        }
        System.out.println();
    }

    private void addMany(int count) {
        for(int i = 0; i < count; i++) {
            addOne();
        }
    }

    private void addOne() {
        new Entry(Math.random()+"", ((int)(Math.random()*50) + 1970)+ "", (int) (Math.random()*50000));
    }

    private void sort(Comparator c) {
        Collections.sort(entries, c);
    }

    private static class NumberComparator implements Comparator {

        @Override
        public int compare(Object ob1, Object ob2) {
            Entry o1 = (Entry) ob1;
            Entry o2 = (Entry) ob2;

            int result = o1.number - o2.number;
            //System.out.format("%s - %s = %s \n", o1.name, o2.name, result);
            return result;
        }

    }

    private static class DateComparator implements Comparator {

        @Override
        public int compare(Object ob1, Object ob2) {
            Entry o1 = (Entry) ob1;
            Entry o2 = (Entry) ob2;

            Date d1, d2;
            try {
                d1 = sdf.parse(o1.date);
                d2 = sdf.parse(o2.date);
            } catch (ParseException ex) {
                Logger.getLogger(SortMe.class.getName()).log(Level.SEVERE, null, ex);
                return 0;
            }

            int result = d1.compareTo(d2);
            //System.out.format("%s - %s = %s \n", o1.name, o2.name, result);
            return result;
        }

    }

    private static class NameComparator implements Comparator {

        @Override
        public int compare(Object ob1, Object ob2) {
            Entry o1 = (Entry) ob1;
            Entry o2 = (Entry) ob2;
            int result = o1.name.compareTo(o2.name);
            //System.out.format("%s - %s = %s \n", o1.name, o2.name, result);
            return result;
        }

    }

    private class Entry {
        private final String name, date;
        private final int number;

        private Entry(String name, String date, int number) {
            this.name = name;
            this.date = date;
            this.number = number;
            entries.add(this);
        }

        @Override
        public String toString() {
            return "Entry{" + "name=" + name + ", date=" + date + ", number=" + number + '}';
        }

    }

}