public class OrderListEntity {

    /**
     * @deprecated  对象集合的处理
     * @param aData 集合a
     * @param bData 集合b
     * @return 返回集合a比集合b多出来的部分, 通过id判断
     */
    public static List<OrderListEntity> AHasMoreThanBData(
            List<OrderListEntity> aData, List<OrderListEntity> bData) {

        List<OrderListEntity> moreEntities = new ArrayList<>();
        if (aData == null && bData == null) {
            return moreEntities;
        }

        for (OrderListEntity sAData : aData) {
            boolean isSame = false;
            for (OrderListEntity sBData : bData) {
                if (sAData.isTheSame(sBData)) {
                    isSame = true;
                    break;
                }
            }
            if (!isSame) {
                moreEntities.add(sAData);
            }
        }

        return moreEntities;
    }

    public OrderListEntity() {

    }

    public OrderListEntity(int id, String content) {
        this.id = id;
        this.content = content;
    }

    private int id;

    private String content;

    public int getId() {
        return id;
    }

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

    public String getContent() {
        return content;
    }

    public void setContent(String content) {
        this.content = content;
    }

    public boolean isTheSame(OrderListEntity entity) {
        if (entity == null) return false;
        return this.id == entity.getId();
    }

    @Override
    public String toString() {
        return "{" +
                "id=" + id +
                ", content='" + content + '\'' +
                '}';
    }
}

public static void main(String[] args) {

        OrderListEntity entity1 = new OrderListEntity(1, "内容1");
        OrderListEntity entity2 = new OrderListEntity(2, "内容2");
        OrderListEntity entity3 = new OrderListEntity(3, "内容3");

        OrderListEntity entity4 = new OrderListEntity(4, "内容4");
        OrderListEntity entity5 = new OrderListEntity(5, "内容5");
        OrderListEntity entity6 = new OrderListEntity(6, "内容6");
        OrderListEntity entity7 = new OrderListEntity(1, "内容1");

        List<OrderListEntity> list1 = new ArrayList<>();
        list1.add(entity1);
        list1.add(entity2);
        list1.add(entity3);
        list1.add(entity4);

        List<OrderListEntity> list2 = new ArrayList<>();
        list2.add(entity4);
        list2.add(entity5);
        list2.add(entity6);


        //内容相同的两个对象也属于两个对象，contains是判断对象是否存在，创建另外一个对象，内容相同也是不存在的
        System.out.println("是否存在：" + list1.contains(entity7));
        System.out.println("是否相同-(equals)：" + entity1.equals(entity7));
        System.out.println("是否相同-(==)：" + (entity1 == entity7));
        //通过比较id是否相同判断是否是一个订单
        System.out.println("是否相同-(id比较)：" + entity1.isTheSame(entity7));

        System.out.println("\n");

        System.out.println("list1比list2多出来的部分：");

        //listEntities1比listEntities2多出来的部分
        List<OrderListEntity> orderListEntities1 = OrderListEntity.AHasMoreThanBData(list1, list2);
        for (OrderListEntity orderListEntity : orderListEntities1) {
            System.out.print(orderListEntity.toString());
        }

        System.out.println("\n");

        System.out.println("list2比list1多出来的部分：");

        //listEntities2比listEntities1多出来的部分
        List<OrderListEntity> orderListEntities2 = OrderListEntity.AHasMoreThanBData(list2, list1);
        for (OrderListEntity orderListEntity : orderListEntities2) {
            System.out.print(orderListEntity.toString());
        }


    }

 运行结果：