update,

_resources/it114105/itp4507/Assignment/20-21/src/Caretaker.java

@@ -0,0 +1,35 @@
+
+import java.util.Stack;
+
+/*
+ * To change this license header, choose License Headers in Project Properties.
+ * To change this template file, choose Tools | Templates
+ * and open the template in the editor.
+ */
+/**
+ *
+ * @author jerrykwok
+ */
+public class Caretaker {
+
+    private Stack<LunchSetMemento> undoList;
+
+    public Caretaker() {
+        undoList = new Stack();
+    }
+
+    public void saveLunchSet(LunchSetMemento lunchSetMemento) {
+        undoList.push(lunchSetMemento);
+    }
+
+    public void undo() {
+        if (undoList.isEmpty()) {
+            System.out.println("UndoList is Empty");
+            return;
+        }
+        LunchSetMemento obj = undoList.pop();
+
+        obj.restore();
+    }
+
+}