17.1.java

import java.util.List;
import java.util.ArrayList;

public class MasterSubscription {
   private List<MagazineOrder> orders;

   public MasterSubscription() {
      orders = new ArrayList<MagazineOrder>();
   }

   public void addOrder(MagazineOrder theOrder) {
      orders.add(theOrder);
   }

   public int getTotalMagazines() {
      int total = 0;
      for (MagazineOrder magazine : orders) {
         total += magazine.getNumMagazines();
      }
      return total;
   }

   public int removeMagazine(String magazineName) {
      int ret = 0;
      for (int i = 0; i < orders.size(); i++) {
         if (orders.get(i).getName().equals(magazineName)) {
            ret += orders.get(i).getNumMagazines();
            orders.remove(i);
            i--;
         }
      }
      return ret;
   }
}

17.2.java

import java.util.Random;

public class Map {
   private int[][] map;
   private int rows;
   private int cols;

   public Map(int rows, int cols) {
      this.rows = rows;
      this.cols = cols;
   }

   public void generateMap() {
      Random rand = new Random();
      map = new int[rows][cols];
      for (int i = 0; i < rows; i++) {
         for (int j = 0; j < cols; j++) {
            map[i][j] = rand.nextInt(4) + 1;
         }
      }
   }

   public void showMap() {
      for (int i = 0; i < rows; i++) {
         for (int j = 0; j < cols; j++) {
            System.out.print(map[i][j] + " ");  
         }
         System.out.println();
      }
   }

   public int getElement(int row, int col) {
      return map[row][col];
   }
}

17.3.1.java

public class MusicSong {
   private String songName;
   private String songArtist;
   private int songLength;

   public MusicSong(String name, String artist, int length) {
      this.songName = name;
      this.songArtist = artist;
      this.songLength = length;
   }
    
   public int getSongLength() {
      return songLength;
   }
}

17.3.2.java

import java.util.ArrayList;

public class MP3Player {
   private ArrayList<MusicSong> mp3PlayerSongs;
    
   public MP3Player() {
      mp3PlayerSongs = new ArrayList<MusicSong>();
   }
    
   public void addSong(MusicSong newSong) {
      mp3PlayerSongs.add(newSong);
   }
         
   public int totalSongTime() {
      int total = 0;
      for (MusicSong song : mp3PlayerSongs) {
         total += song.getSongLength();
      }
      return total;
   }
}

17.4.java

public class Rectangle {
   private int height, width;
    
   public Rectangle(int rectHeight, int rectWidth) {
      this.height = rectHeight;
      this.width = rectWidth;
   }

   public int getHeight() {
      return height;
   }
   
   public int getWidth() {
      return width;
   }

   public int getPerimeter() {
      return (height * 2) + (width * 2);
   }

   public int getArea() {
      return height * width;
   }
}