diff --git a/README.md b/README.md
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+++ b/README.md
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+### 5.15
+## Order class
+기본적인 생성자 선언
+아이디를 찾을 수 있도록 매서드 선언
+
+## OrderRepository class
+모든 아이디의 리스트를 확인 할 수 있는 매서드 추가 -> ArrayList로 생성
+특정 아이디를 찾을 수 있는 매서드 추가
+모든 리스트를 삭제할 수 있는 매서드 추가
diff --git a/src/jihoon/Hello.java b/src/jihoon/Hello.java
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+++ b/src/jihoon/Hello.java
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+package jihoon;
+
+public class Hello {
+    public static void main(String[] args) {
+        System.out.println("Hello world");
+    }
+}
diff --git a/src/jihoon/JihoonPractice.java b/src/jihoon/JihoonPractice.java
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+++ b/src/jihoon/JihoonPractice.java
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+package jihoon;
+
+public class JihoonPractice {
+    public static void greet() {
+        System.out.println("reqeqw");
+    }
+    public static void main(String[] args) {
+
+        greet();
+    }
+}
diff --git a/src/jihoon/Order/Order.java b/src/jihoon/Order/Order.java
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+++ b/src/jihoon/Order/Order.java
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+package jihoon.Order;
+
+// Order.java
+public class Order {
+    private Long memberId;         // 주문자 회원 ID
+    private String itemName;       // 상품명
+    private int itemPrice;         // 상품 가격
+    private int discountPrice;     // 할인 금액
+    private int finalPrice;        // 최종 결제 금액
+
+    public Order(Long memberId, String itemName, int itemPrice, int discountPrice, int finalPrice) {
+        this.memberId = memberId;
+        this.itemName = itemName;
+        this.itemPrice = itemPrice;
+        this. finalPrice = finalPrice;
+
+    }
+    public Long getId() {
+        return memberId;
+    }
+    // 생성자, 계산 메서드, 출력 메서드 등 포함
+}
diff --git a/src/jihoon/Order/OrderRepository.java b/src/jihoon/Order/OrderRepository.java
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+++ b/src/jihoon/Order/OrderRepository.java
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+package jihoon.Order;
+import java.util.List;
+import java.util.ArrayList;
+public class OrderRepository {
+    private List<Order> orders = new ArrayList<>();
+
+    public void save(Order order) {
+        orders.add(order);
+    }
+
+    public List<Order> findAll() {
+        return orders;
+    }
+
+    public Order findById(int id) {
+        for (Order order : orders) {
+            if (order.getId() == id) {
+                return order;
+            }
+
+        }
+        return null;
+    }
+
+    public void clear() {
+        orders.clear();
+    }
+}
+