step1

src/hacker/DescendingHackerThread.java

 package hacker;
 
-public class DescendingHackerThread {
+public class DescendingHackerThread extends Thread {
+    private Vault vault;
+
+    public static final int MAX_PASSWORD = 9999;
+
+
+    public DescendingHackerThread(Vault vault) {
+        this.vault = vault;
+
+        this.setName(this.getClass().getSimpleName());
+    }
+
+    public void run() {
+
+
+        for (int x = MAX_PASSWORD; x >= 0; x--) {
+
+
+            if (vault.isCorrectPassword(x)) {
+
+                System.out.println("success " + this.getName() + "the correct password " + x);
+
+
+                System.exit(0);
+            }
+        }
+    }
+
 }