parent
fdde3c4d2a
commit
030545e782
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public class CoinInventory {
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private int[] coinCounts; //cp (pennies), sp (dimes), ep (half-dollars), gp (dollar bills), pp (five dollar bills)
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private int weight; //The weight is the sum of all the coins.
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public CoinInventory() {
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coinCounts = new int[5];
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}
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public void setCoins(int[] a) {
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coinCounts = a;
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}
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public int[] getCoins() {
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return coinCounts;
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}
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public void setWeight(int w) {
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weight = w;
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}
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public int getWeight() {
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return weight;
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}
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}
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public class Item {
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private String description;
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private int weight;
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public Item(String description, int weight) {
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this.description = description;
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this.weight = weight;
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}
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public int getWeight() {
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return weight;
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}
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public String getDescription() {
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return description;
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}
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}
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@ -0,0 +1,77 @@
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//The design among these 3 classes needs improvement, and the code has a couple of bugs, too.
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//Improve the design and fix the bugs.
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//The public interface of Player should remain the same as it is now.
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//Hints:
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//Avoid duplicate data
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//Methods and instance data should have high cohesion
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//Coupling should be loose between classes
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import java.util.*;
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public class Player {
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private String name;
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private CoinInventory coinInventory;
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private ArrayList<Item> otherInventory;
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private int encumbrance;
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public Player(String name) {
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this.name = name;
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coinInventory = new CoinInventory();
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otherInventory = new ArrayList<Item>();
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encumbrance = 0;
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}
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public void addItem(Item item) {
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otherInventory.add(item);
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}
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public void collectMoney(int cp, int sp, int ep, int gp, int pp) {
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int[] moneys = coinInventory.getCoins();
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moneys[0] += cp;
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moneys[1] += sp;
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moneys[2] += ep;
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moneys[3] += gp;
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moneys[4] += pp;
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coinInventory.setCoins(moneys);
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}
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public double getRunningSpeed() {
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double speed = 5 * (1 - getEncumbrance() / 1000.0); //Speed 5 if unencumbered; speed 0 if 1000 units carried or more.
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if (speed < 0) {
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return 0;
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}
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else {
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return speed;
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}
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}
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public double getMoneyValue() {
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int[] moneys = coinInventory.getCoins();
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return .01 * moneys[0] + .1 * moneys[1] + .5 * moneys[2] + 1 * moneys[3] + 5 * moneys[4];
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}
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public int getEncumbrance() {
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int[] moneys = coinInventory.getCoins();
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return moneys[0] + moneys[1] + moneys[2] + moneys[3] + moneys[4] + encumbrance;
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}
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//Test method.
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public static void main(String[] args) {
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Player p = new Player("Whistlestick");
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Item sword = new Item("Magic sword +2", 20);
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Item shield = new Item("Normal shield", 40);
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p.addItem(sword);
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p.addItem(shield);
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if (p.getEncumbrance() != 60) throw new RuntimeException("getEncumbrance() should be 60, not " + p.getEncumbrance());
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p.collectMoney(10,2,0,40,2);
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if (p.getEncumbrance() != 60+54) throw new RuntimeException("getEncumbrance() should be 114, not " + p.getEncumbrance());
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if (p.getMoneyValue() != 50.3) throw new RuntimeException("getMoneyValue() should be 50.3, not " + p.getMoneyValue());
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p.collectMoney(0,0,0,6,0);
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if (p.getEncumbrance() != 120) throw new RuntimeException("getEncumbrance() should be 120, not " + p.getEncumbrance());
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if (p.getRunningSpeed() != 4.4) throw new RuntimeException("getRunningSpeed() should be 4.4, not " + p.getRunningSpeed());
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System.out.println("All tests passed.");
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}
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}
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@ -0,0 +1,26 @@
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public class CoinInventory {
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private int[] coinCounts; //cp (pennies), sp (dimes), ep (half-dollars), gp (dollar bills), pp (five dollar bills)
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public CoinInventory() {
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coinCounts = new int[5];
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}
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public void collectMoney(int cp, int sp, int ep, int gp, int pp) {
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coinCounts[0] += cp;
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coinCounts[1] += sp;
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coinCounts[2] += ep;
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coinCounts[3] += gp;
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coinCounts[4] += pp;
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}
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public double getMoneyValue() {
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return .01 * coinCounts[0] + .1 * coinCounts[1] + .5 * coinCounts[2] + 1 * coinCounts[3] + 5 * coinCounts[4];
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}
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public int getWeight() {
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return coinCounts[0] + coinCounts[1] + coinCounts[2] + coinCounts[3] + coinCounts[4];
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}
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}
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@ -0,0 +1,18 @@
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public class Item {
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private String description;
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private int weight;
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public Item(String description, int weight) {
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this.description = description;
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this.weight = weight;
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}
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public int getWeight() {
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return weight;
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}
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public String getDescription() {
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return description;
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}
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}
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@ -0,0 +1,69 @@
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//The design among these 3 classes needs improvement, and the code has a couple of bugs, too.
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//Improve the design and fix the bugs.
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//The public interface of Player should remain the same as it is now.
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//Hints:
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//Avoid duplicate data
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//Methods and instance data should have high cohesion
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//Coupling should be loose between classes
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import java.util.*;
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public class Player {
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private String name;
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private CoinInventory coinInventory;
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private ArrayList<Item> otherInventory;
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public Player(String name) {
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this.name = name;
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coinInventory = new CoinInventory();
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otherInventory = new ArrayList<Item>();
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}
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public void addItem(Item item) {
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otherInventory.add(item);
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}
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public void collectMoney(int cp, int sp, int ep, int gp, int pp) {
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coinInventory.collectMoney(cp, sp, ep, gp, pp);
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}
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public double getRunningSpeed() {
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double speed = 5 * (1 - getEncumbrance() / 1000.0); //Speed 5 if unencumbered; speed 0 if 1000 units carried or more.
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if (speed < 0) {
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return 0;
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}
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else {
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return speed;
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}
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}
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public double getMoneyValue() {
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return coinInventory.getMoneyValue();
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}
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public int getEncumbrance() {
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int encumbrance = 0;
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for(Item i : otherInventory) encumbrance += i.getWeight();
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return coinInventory.getWeight() + encumbrance;
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}
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//Test method.
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public static void main(String[] args) {
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Player p = new Player("Whistlestick");
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Item sword = new Item("Magic sword +2", 20);
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Item shield = new Item("Normal shield", 40);
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p.addItem(sword);
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p.addItem(shield);
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if (p.getEncumbrance() != 60) throw new RuntimeException("getEncumbrance() should be 60, not " + p.getEncumbrance());
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p.collectMoney(10,2,0,40,2);
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if (p.getEncumbrance() != 60+54) throw new RuntimeException("getEncumbrance() should be 114, not " + p.getEncumbrance());
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if (p.getMoneyValue() != 50.3) throw new RuntimeException("getMoneyValue() should be 50.3, not " + p.getMoneyValue());
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p.collectMoney(0,0,0,6,0);
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if (p.getEncumbrance() != 120) throw new RuntimeException("getEncumbrance() should be 120, not " + p.getEncumbrance());
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if (p.getRunningSpeed() != 4.4) throw new RuntimeException("getRunningSpeed() should be 4.4, not " + p.getRunningSpeed());
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System.out.println("All tests passed.");
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}
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}
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@ -0,0 +1,17 @@
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Designing good classes
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----------------------
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* To guide design on the class level, ask: "How will this class be used?"
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* A class should represent one coherent abstraction or concept.
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* Look for code reuse opportunities (would this class be useful elsewhere?)
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* When working with a class externally, you should not have to understand the internal implementation.
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* Every constructor and public method should leave the instance variables in a consistent and correct state for the next public method call.
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* Generally avoid going over 7 (plus or minus 2) instance variables in a class.
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* Do not repeat data unless truly necessary.
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* Do not give variables more scope than they require.
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