Add BinarySearchHacker thread and tested it and add the printing of the number...

Add BinarySearchHacker thread and tested it and add the printing of the number of attempts for each hacker.

src/AscendingHackerThread.java

@@ -8,8 +8,11 @@ public class AscendingHackerThread extends Hacker {
     @Override
     public void hack() {
         for (int guess = 0; guess <= 9999; guess++) {
+            attempts++;
             if (vault.isCorrectPassword(guess)) {
                 System.out.println(this.getName() + " guessed the password " + guess);
+                // print attempts from all hackers before exiting
+                Hacker.printAllAttempts();
                 System.exit(0);
             }
         }

src/BinarySearchHackerThread.java

+public class BinarySearchHackerThread extends Hacker {
+
+    public BinarySearchHackerThread(Vault vault) {
+        super(vault);
+        this.setName("BinarySearchHackerThread");
+        this.setPriority(Thread.MAX_PRIORITY);
+    }
+
+    @Override
+    public void hack() {
+        int low = 0;
+        int high = 9999;
+
+        while (low <= high) {
+            int mid = (low + high) / 2;
+            attempts++;
+            if (vault.isCorrectPassword(mid)) {
+                System.out.println(this.getName() + " guessed the password.");
+                Hacker.printAllAttempts();
+                System.exit(0);
+            } else if (mid < vault.getSecretCode()) {
+                low = mid + 1;
+            } else {
+                high = mid - 1;
+            }
+        }
+    }
+    
+}

src/DescendingHackerThread.java

@@ -5,12 +5,14 @@ public class DescendingHackerThread extends Hacker {
         this.setName("DescendingHackerThread");
         this.setPriority(Thread.MAX_PRIORITY);
     }
-    
+
     @Override
     public void hack() {
         for (int guess = 9999; guess >= 0; guess--) {
+            attempts++;
             if (vault.isCorrectPassword(guess)) {
                 System.out.println(this.getName() + " guessed the password " + guess);
+                Hacker.printAllAttempts();
                 System.exit(0);
             }
         }

src/Hacker.java

+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+
 public abstract class Hacker extends Thread {
     protected final Vault vault;
+    private static final List<Hacker> ALL_HACKERS = Collections.synchronizedList(new ArrayList<>());
+    protected int attempts = 0;
 
     public Hacker(Vault vault) {
         this.vault = vault;
+        ALL_HACKERS.add(this);
     }
 
     public abstract void hack();
-    
+
     @Override
     public void run() { hack(); }
+
+    public int getAttempts() { return attempts; }
+
+    // helper to print attempts of all hackers
+    public static void printAllAttempts() {
+        synchronized (ALL_HACKERS) {
+            for (Hacker h : ALL_HACKERS) {
+                System.out.println(h.getName() + " attempted: " + h.getAttempts() + " times");
+            }
+        }
+    }
 }

src/Main.java

@@ -3,10 +3,12 @@ public class Main {
         Vault vault = new Vault();
         Thread ascendingHacker = new AscendingHackerThread(vault);
         Thread descendingHacker = new DescendingHackerThread(vault);
+        Thread binarySearchHacker = new BinarySearchHackerThread(vault);
         Thread police = new PoliceThread(10);
 
         ascendingHacker.start();
         descendingHacker.start();
+        binarySearchHacker.start();
         police.start();
     }
 }

src/PoliceThread.java

@@ -13,6 +13,7 @@ public class PoliceThread extends Thread {
                 Thread.sleep(1000);
             }
             System.out.println("Police have arrived! Game over for hackers.");
+            Hacker.printAllAttempts();
             System.exit(0);
         } catch (InterruptedException e) {
             Thread.currentThread().interrupt();

src/Vault.java

@@ -22,6 +22,10 @@ public class Vault {
         return this.secretCode == guess;
     }
 
+    public int getSecretCode() {
+        return secretCode;
+    }
+
     private static int randBetween(int min, int max) {
         if (min > max) throw new IllegalArgumentException("min > max");
         if (max == Integer.MAX_VALUE) {