Upload Lab5 solution

Lab5/solution/Adapter.java

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+package solution;
+
+public class Adapter {
+	public static final String[] BEVERAGES = new String[] {
+			"Caff� Americano", "Caff� Mocha", "Caff� Latte", 
+			"Cappuccino", "Caramel Macchiato", "Espresso" };
+
+	public String getBeverage(String s){
+		// Return null if nothing is similar
+		int min = Integer.MAX_VALUE;
+		String min_string = null;
+		// Compare each word in the array with the query word
+		for ( String b : BEVERAGES ) {
+			WagnerFischer ob = new WagnerFischer( s, b );
+			int dist = ob.getDistance();
+			// Record the minimum
+			if ( dist <= 3 && dist < min ) {
+				min = dist;
+				min_string = b;
+			}
+		}
+		return min_string;
+	}
+}

Lab5/solution/Observer.java

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+package solution;
+
+public class Observer {
+	private int id;
+	private Subject subject;
+
+	public Observer(int id) {
+		this.id = id;
+	}
+
+	public int getID(){
+		return id;
+	}
+
+	public void subscribe(Subject sub) {
+		this.subject = sub;
+	}
+
+	public void unsubscribe() {
+		subject.unregister(this);
+	}
+
+	public void update(){
+		// Get the message first
+		int order = Integer.valueOf(subject.getMessage());
+		// React based on the message
+		if ( order >= getID()+7 || order == getID() ) {
+			unsubscribe();
+		}
+	}
+}

Lab5/solution/Subject.java

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+package solution;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class Subject {
+	private List<Observer> observers;
+	private String message;
+	private boolean changed;
+
+	public Subject() {
+		observers = new ArrayList<Observer>();
+		message = null;
+		changed = false;
+	}
+
+	public void register(Observer obj) {
+		if ( !observers.contains(obj) ) observers.add(obj);
+	}
+
+	public void unregister(Observer obj) {
+		observers.remove(obj);
+	}
+
+	public void notifyObservers() {
+		// if nothing is changed, we can skip this
+		if ( !changed ) return;
+
+		// we need to use a new list because observers may unsubscribe from the list
+		// and this might cause unexpected behaviours
+		// forEach is a faster way to loop over a list (see Java 1.8 lambda expression)
+		new ArrayList<>(observers).forEach( o -> o.update() );
+
+		// another approach to do it is to traverse the list starting from the end
+		for ( int i = observers.size()-1; i >= 0; --i ) {
+			observers.get(i).update();
+		}
+
+		// reset parameter
+		changed = false;
+	}
+
+	public void setMessage(String msg) {
+		this.message=msg;
+		this.changed=true;
+		notifyObservers();
+	}
+
+	public String getMessage() {
+		return message;
+	}
+
+	public void setChanged(boolean changed) {
+		this.changed = changed;
+	}
+
+	public List<Observer> getQueue() {
+		return observers;
+	}
+}

Lab5/solution/Test.java

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+package solution;
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+
+public class Test {
+	public static final String MESSAGE_WELCOME = "Welcome to Starbucks!";
+	public static final String MESSAGE_SEPERATOR = "===============================================";
+	public static final String MESSAGE_SELECT = "Select functions:\n 1) Order\n 2) An order is ready\n 3) Check the queue\n 4) Exit";
+	public static final String MESSAGE_SELECT_ONE = "Which drink you would like to order?";
+	public static final String MESSAGE_SELECT_TWO = "Which order is ready?";
+	public static final String MESSAGE_SELECT_THREE = "The following ids are in the queue:";
+	public static final String MESSAGE_SELECT_FOUR = "Goodbye!~";
+	public static final String MESSAGE_ERROR = "Please enter the number.";
+
+	public static void main(String[] args) {
+		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+
+		// TODO: possible setup
+		Subject starbucks = new Subject();
+		Adapter adapter = new Adapter();
+		int id = 1;
+
+		try {
+			System.out.println(MESSAGE_WELCOME);
+			loop: while(true) {
+				System.out.println(MESSAGE_SEPERATOR);
+				System.out.println(MESSAGE_SELECT);
+				String in = br.readLine();
+				switch(in){
+				case "1":
+					System.out.println(MESSAGE_SELECT_ONE);
+					String drink = br.readLine();
+					// TODO: give an ordered id
+					// order is successful only if edit distance <= 3
+					String beverage = adapter.getBeverage(drink); 
+					if ( beverage != null ) {
+						Observer customer = new Observer(id++);
+						starbucks.register(customer);
+						customer.subscribe(starbucks);
+						System.out.println(String.format("%s is ordered and your order id is %d", beverage, customer.getID())); //success
+					} else {
+						System.out.println(String.format("%s not found.", drink)); //fail
+					}
+					break;
+				case "2":
+					System.out.println(MESSAGE_SELECT_TWO);
+					String order = br.readLine();
+					// TODO: act appropriately according to your design
+					starbucks.setMessage(order);
+					break;
+				case "3":
+					System.out.println(MESSAGE_SELECT_THREE);
+					// print all id in the queue
+					starbucks.getQueue().forEach(o -> System.out.println(o.getID()));
+					break;
+				case "4":
+					break loop;
+				default:
+					System.out.println(MESSAGE_ERROR);
+				}
+			}
+
+			br.close();
+		} catch (IOException e) {
+			e.printStackTrace();
+		}
+	}
+
+}

Lab5/solution/WagnerFischer.java

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+package solution;
+public class WagnerFischer {
+    private char[] s1;
+    private char[] s2;
+
+    public WagnerFischer(String s1, String s2) {
+        this.s1 = s1.toLowerCase().toCharArray();
+        this.s2 = s2.toLowerCase().toCharArray();
+    }
+
+    private int min(int a, int b, int c) {
+        return Math.min(a, Math.min(b, c));
+    }
+
+    /**
+     * Using Dynamic Programming, the Wagner-Fischer algorithm is able to 
+     * calculate the edit distance between two strings.
+     * @return edit distance between s1 and s2
+     */
+    public int getDistance() {
+        int[][] dp = new int[s1.length + 1][s2.length + 1];
+        for (int i = 0; i <= s1.length; dp[i][0] = i++);
+        for (int j = 0; j <= s2.length; dp[0][j] = j++);
+
+        for (int i = 1; i <= s1.length; i++) {
+            for (int j = 1; j <= s2.length; j++) {
+                if (s1[i - 1] == s2[j - 1]) {
+                    dp[i][j] = dp[i - 1][j - 1];
+                } else {
+                    dp[i][j] = min(dp[i - 1][j] + 1, dp[i][j - 1] + 1, 
+                    		dp[i - 1][j - 1] + 1);
+                }
+            }
+        }
+        return dp[s1.length][s2.length];
+    }
+
+    public static void main(String[] args) {
+        WagnerFischer wf = new WagnerFischer("Caffe Mocha", "coffee moka");
+        System.out.println(wf.getDistance());
+        wf = new WagnerFischer("Frappuccino", "fappiccino");
+        System.out.println(wf.getDistance());
+    }
+
+}

README.md

@@ -23,7 +23,7 @@ You need to have some backgrounds on Java/Database/git in order to complete the
 |     | 5    | No lab at week 5 | |
 | 4   | 6    | [UML](./lab_UML.pdf) | [Solution](./uml_lab_sample_answer.pdf) |
 |     | 7    | No lab at week 7 | |
-| 5   | 8    | [Design Pattern](./lab6/lab_design_pattern.pdf) |
+| 5   | 8    | [Design Pattern](./Lab5/lab_design_pattern.pdf) |[Solution](./Lab5/solution/)|
 | 6   | 9    | [Refactoring](./refactoring-lab/README.md) |