0

当检查实例与其他实例相等时，我得到

java.lang.StackOverflowError.

因为存在双向关系，所以我的Override equal method调用equal()函数相互递归。我应该删除一侧override equal method的一张支票相等条件吗？有什么更好的方法？一些 PG 建议我使用EqualsBuilderApache。

订单项.java

 public class OrderItem {
            private String id;
            private Order order;

            public OrderItem(String id, Order order) {
                this.id = id;
                this.order = order;
            }

            public void setId(String id) {
                this.id = id;
            }

            public String getId() {
                return id;
            }

            public void setOrder(Order order) {
                this.order = order;
            }

            public Order getOrder() {
                return order;
            }

            @Override
            public boolean equals(Object object) {
                if (this == object) {
                    return true;
                }
                if (!(object instanceof OrderItem)) {
                    return false;
                }
                final OrderItem other = (OrderItem)object;
                if (!(id == null ? other.id == null : id.equals(other.id))) {
                    return false;
                }
                if (!(order == null ? other.order == null : order.equals(other.order))) {
                    return false;
                }
                return true;
            }
        }

订单.java

        public class Order {
            private String id;
            private List<OrderItem> orderItemList;

            public Order(String id) {
                this.id = id;
            }

            public void setId(String id) {
                this.id = id;
            }

            public String getId() {
                return id;
            }

            public void setOrderItemList(List<OrderItem> orderItemList) {
                this.orderItemList = orderItemList;
            }

            public List<OrderItem> getOrderItemList() {
                return orderItemList;
            }

            @Override
            public boolean equals(Object object) {
                if (this == object) {
                    return true;
                }
                if (!(object instanceof Order)) {
                    return false;
                }
                final Order other = (Order)object;
                if (!(id == null ? other.id == null : id.equals(other.id))) {
                    return false;
                }
                if (!(orderItemList == null ? other.orderItemList == null : orderItemList.equals(other.orderItemList))) {
                    return false;
                }
                return true;
            }
        }

测试

        public static void main(String[] args) {
            Order order1 = new Order("1");
            List<OrderItem> orderItemList = new ArrayList<OrderItem>();
            orderItemList.add(new OrderItem("1", order1));
            orderItemList.add(new OrderItem("2", order1));
            order1.setOrderItemList(orderItemList);


            Order order2 = new Order("1");
            List<OrderItem> orderItemList2 = new ArrayList<OrderItem>();
            orderItemList2.add(new OrderItem("1", order2));
            orderItemList2.add(new OrderItem("2", order2));
            order2.setOrderItemList(orderItemList2);

            if(order1.equals(order2)) {
                System.out.println("Equal");
            } else {
                System.out.println("Not Equal");
            }
        }
4

1 回答 1

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我会重写它以仅使用id属性进行相等性检查。但这很重要hashcode()：如果您希望实体在 Java 集合中正确运行，请不要忘记覆盖该方法。

于 2012-09-24T09:57:58.270 回答