TreeSetTest.java Source code

Introduction

Here is the source code for TreeSetTest.java

Source

/*
   This program is a part of the companion code for Core Java 8th ed.
   (http://horstmann.com/corejava)
    
   This program is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.
    
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
    
   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

/**
   @version 1.10 2004-08-02
   @author Cay Horstmann
*/

import java.util.Comparator;
import java.util.SortedSet;
import java.util.TreeSet;

/**
   This program sorts a set of item by comparing
   their descriptions.
*/
public class TreeSetTest {
    public static void main(String[] args) {
        SortedSet<Item> parts = new TreeSet<Item>();
        parts.add(new Item("Toaster", 1234));
        parts.add(new Item("Widget", 4562));
        parts.add(new Item("Modem", 9912));
        System.out.println(parts);

        SortedSet<Item> sortByDescription = new TreeSet<Item>(new Comparator<Item>() {
            public int compare(Item a, Item b) {
                String descrA = a.getDescription();
                String descrB = b.getDescription();
                return descrA.compareTo(descrB);
            }
        });

        sortByDescription.addAll(parts);
        System.out.println(sortByDescription);
    }
}

/**
   An item with a description and a part number.
*/
class Item implements Comparable<Item> {
    /**
       Constructs an item.
       @param aDescription the item's description
       @param aPartNumber the item's part number
    */
    public Item(String aDescription, int aPartNumber) {
        description = aDescription;
        partNumber = aPartNumber;
    }

    /**
       Gets the description of this item.
       @return the description
    */
    public String getDescription() {
        return description;
    }

    public String toString() {
        return "[descripion=" + description + ", partNumber=" + partNumber + "]";
    }

    public boolean equals(Object otherObject) {
        if (this == otherObject)
            return true;
        if (otherObject == null)
            return false;
        if (getClass() != otherObject.getClass())
            return false;
        Item other = (Item) otherObject;
        return description.equals(other.description) && partNumber == other.partNumber;
    }

    public int hashCode() {
        return 13 * description.hashCode() + 17 * partNumber;
    }

    public int compareTo(Item other) {
        return partNumber - other.partNumber;
    }

    private String description;
    private int partNumber;
}