了解列表为何固定抽象方法类型

Question

我用两个抽象方法创建了一个类。

在一种方法中，根据抽象方法List中的返回类型的要求，在列表中返回通用类型U。

在我的第二种方法中，我只是按抽象方法中返回类型的要求返回U，但出现类型错误错误CS0029：无法隐式转换类型LB.HexSphereBuild.HexTile' toHexTile'

我不明白为什么这是隐式转换？特别是因为所有类型都在LB.HexSphereBuild命名空间下，除了我的使用LB.HexSphereBuild的公共抽象类AStarFindPath之外；

请帮忙

using System.Collections;

using System.Collections.Generic;

using UnityEngine;

using LB.Managers;

using LB.HexSphereBuild;

namespace LB.AStarPathFinding

{

    public abstract class AStarFindPath<T,U> : MonoBehaviour{

        public virtual void FindPath<T>(Vector3 startPos, Vector3 targetPos) {

        }

        // Method 1

        public abstract U NodeFromWorldPoint<T,U> (Vector3 worldPos);

        // Method 2

        public abstract List<U> GetNodeNeighbours<U> (U node);

    }

}

这是继承我的抽象类的类

using System.Collections;

using System.Collections.Generic;

using UnityEngine;

using LB.Managers;

using LB.AStarPathFinding;

namespace LB.HexSphereBuild

{

    [RequireComponent (typeof(PlanetBuildManager))]

    public class AStarHexSphere: AStarFindPath<Hexsphere,HexTile>

    {

        private HexSphere _hexSphereObj;

        void Awake ()

        {

            // Reference to HexSphere 

            _hexSphereObj = gameObject.GetComponent<PlanetBuildManager> ().hexSphereObj;

        }

        override public HexTile NodeFromWorldPoint<HexSphere,HexTile> (Vector3 worldPos )

        {

            int startNodeIndex = _hexSphereObj.GetHexIndexFromPoint (worldPos);

            int startNodeIndex = _hexSphereObj.GetHexIndexFromPoint (worldPos);

            HexTile startHex =  _hexSphereObj.Hexes[startNodeIndex];// error CS0029: Cannot implicitly convert type `LB.HexSphereBuild.HexTile' to `HexTile'

            return startHex;

        }

        override public List<HexTile> GetNodeNeighbours<HexTile> (HexTile node )

        {

            List<HexTile> neighbours = new List<HexTile>();

            List<int> hexNeighboursIndices = new List<int>();

            int hexIndex =0;

            _hexSphereObj.GetNeighbors (hexIndex, ref hexNeighboursIndices);

            return neighbours;

        }

Answer 1

您已经定义了T和U，再次在方法中定义它们意味着T所有方法中的可能是不同的类型。那不是您想要的，删除方法上的泛型：public abstract class AStarFindPath<T,U> : MonoBehaviour{&nbsp; &nbsp; public virtual void FindPath(Vector3 startPos, Vector3 targetPos)&nbsp;&nbsp; &nbsp; {&nbsp; &nbsp; }&nbsp; &nbsp; // Method 1&nbsp; &nbsp; public abstract U NodeFromWorldPoint(Vector3 worldPos);&nbsp; &nbsp; // Method 2&nbsp; &nbsp; public abstract List<U> GetNodeNeighbours(U node);}