Question

我有一些要在送货路线中装卸的订单，一个路线可以分配一个OrderDocument以便装卸，或同时装两者。每个订单文档都通过分配的路径中的索引进行排序。因此，该类如下所示：

class OrderDocument implements Comparable<ModelTask>{
    int order_id;  // The document ID
    int route_load_id;  // The route this order is assigned to be loaded
    int route_unload_id;  // The route this order is assigned to be loaded, may be same as route_load_id and viceversa
    int route_load_index;  // The index order in load route
    int route_unload_index;  // The index order in unload route
}

然后我有了Route类：

class Route{
    int id; // ID of route, this value should be in OrderDocument.route_load/unload_id
    ArrayList<OrderDocument> orders;  // **I WANT TO SORT THIS LIST**
   ...

因此，我有一个函数，该函数创建一个Route实例并将OrderDocument对象添加到其orders ArrayList中，因此列表应该包含Route.id在route_load_id或{{1 }}

主要问题

如果路由ID在load_id或unload_id中，则我需要按负载/卸载索引对该列表进行排序。实际上，我有以下route_unload_id方法，但是没有用。

Comparator

示例

Route-43中有4个订单，要加载2个，要卸载4个。

private class OrdersComparable implements Comparator<OrderDocument>{
    @Override
    public int compare(OrderDocument x, OrderDocument y) {
        if (x.route_load_id == y.route_load_id)
            return x.route_load_index - y.route_load_index;
        else if (x.route_load_id == y.route_unload_id)
            return x.route_load_index - y.route_unload_index;
        else if (x.route_unload_id == y.route_load_id)
            return x.route_unload_index - y.route_load_index;
        else if (x.route_unload_id == y.route_unload_id)
            return x.route_unload_index - y.route_unload_index;
        else
            return 0;
    }
}

按OrderDocument('order_id':1, 'route_load_id':43, 'route_unload_id':null, 'route_load_index':0, 'route_unload_index':null) OrderDocument('order_id':2, 'route_load_id':43, 'route_unload_id':null, 'route_load_index':2, 'route_unload_index':null) OrderDocument('order_id':3, 'route_load_id':null, 'route_unload_id':43, 'route_load_index':null, 'route_unload_index':1) OrderDocument('order_id':1, 'route_load_id':null, 'route_unload_id':43, 'route_load_index':null, 'route_unload_index':3)的实际顺序：1、2、3、1

需要order_id进行订购：1、3、2、1

Answer 1

如果使用null值（以及可为空的对应类型），则必须检查条件是否不比较null，否则将满足不希望的条件：

class OrderDocument implements Comparable<ModelTask> {
    int order_id;  // The document ID
    Integer route_load_id;  // The route this order is assigned to be loaded
    Integer route_unload_id;  // The route this order is assigned to be loaded, may be same as route_load_id and viceversa
    Integer route_load_index;  // The index order in load route
    Integer route_unload_index;  // The index order in unload route
}

class OrdersComparable implements Comparator<OrderDocument> {
@Override
public int compare(OrderDocument x, OrderDocument y) {
    if (x.route_load_id == y.route_load_id && x.route_load_id != null)
        return Integer.compare(x.route_load_index, y.route_load_index);

    if (x.route_load_id == y.route_unload_id && x.route_load_id != null)
        return Integer.compare(x.route_load_index, y.route_unload_index);

    if (x.route_unload_id == y.route_load_id && x.route_unload_id != null)
        return Integer.compare(x.route_unload_index, y.route_load_index);

    if (x.route_unload_id == y.route_unload_id && x.route_unload_id != null)
        return Integer.compare(x.route_unload_index, y.route_unload_index);

    return 0;
}
}

Java对象可使用许多属性进行比较

1 个答案: