Exercise 18

// class Packer /////////////////////////////////////////////////////

package moving.logic;

import java.util.*;
import moving.domain.Box;
import moving.domain.Thing;

public class Packer {

    private int boxesVolume;
    private ArrayList<Box> boxes;

    public Packer(int boxesVolume) {
        this.boxesVolume = boxesVolume;
        this.boxes = new ArrayList<Box>();
    }

    public List<Box> packThings(List<Thing> things) {
        Box box = new Box(this.boxesVolume);

        // iterate through things in parameter list of things
        for (Thing thing : things) {
            boolean fit = box.addThing(thing); // does box.addThing(thing) actually add the thing?
            if (!fit) {
//                System.out.println(box); // ***DEBUG***
                this.boxes.add(box);
                box = new Box(this.boxesVolume); // this new box isn't "known" to the next thing in the list?
                box.addThing(thing); // this isn't working
//                System.out.println(box); // ***DEBUG***
            }
        }

        return this.boxes;
    }

}

// class Box /////////////////////////////////////////////////////

package moving.domain;

import java.util.*;

public class Box implements Thing {

    private int maximumCapacity;
    private ArrayList<Thing> things;

    public Box(int maximumCapacity) {
        this.maximumCapacity = maximumCapacity;
        this.things = new ArrayList<Thing>();
    }

    public boolean addThing(Thing thing) {
        if (this.getVolume() + thing.getVolume() <= this.maximumCapacity) {
            this.things.add(thing);
            return true;
        } else {
            return false;
        }
    }

    @Override
    public int getVolume() {
        int totalVolume = 0;
        for (Thing thing : this.things) {
            totalVolume += thing.getVolume();
        }
        return totalVolume;
    }

    public String toString() {
        return "Contents of box: " + this.things;
    }

}

// class Item /////////////////////////////////////////////////////

package moving.domain;

public class Item implements Thing, Comparable<Item> {

    private String name;
    private int volume;

    public Item(String name, int volume) {
        this.name = name;
        this.volume = volume;
    }

    public String getName() {
        return this.name;
    }

    @Override
    public int getVolume() {
        return this.volume;
    }

    @Override
    public String toString() {
        return this.name + " (" + this.volume + " dm^3)";
    }

    @Override
    public int compareTo(Item anotherThing) {
        return this.volume - anotherThing.getVolume();
    }

}

// class Main /////////////////////////////////////////////////////

package moving;

import moving.domain.Item;
import moving.domain.Thing;
import java.util.*;
import moving.domain.Box;
import moving.logic.Packer;

public class Main {

    public static void main(String[] args) {
        // test your program here
        List<Thing> things = new ArrayList<Thing>();
        things.add(new Item("passport", 2));
        things.add(new Item("toothbrash", 1));
        things.add(new Item("book", 4));
        things.add(new Item("circular saw", 8));

        // we create a packer which uses boxes whose valume is 10
        Packer packer = new Packer(10);

        // we ask our packer to pack things into boxes
        List<Box> boxes = packer.packThings(things);

        System.out.println("number of boxes: " + boxes.size());

        for (Box box : boxes) {
            System.out.println("  things in the box: " + box.getVolume() + " dm^3");
        }
    }
}