java - 如何使用<>引用类中的方法并传入变量

Question

我正在尝试引用方法shortestPathBetween(N from, N to)来自类(class)

public class DijkstraGraphAnalyzer<N extends Node<N, E>, E extends Edge<N, E>> implements GraphAnalyzer<N, E>

在类(class)MainMenuController传递变量，以便该方法可以在从选择框派生的输入上运行。

我尝试创建该类的局部变量，但它随后要求我添加完全相同的参数 <N, E>到MainMenuController

MainMenuController.java

public <MapPoint> List<MapPoint> shortestPathBetween(MapPoint from, MapPoint to) {
  from = (MapPoint) MainMenuController.source;
  to = (MapPoint) MainMenuController.target;
  List<MapPoint> shortestPathBetween = dga.shortestPathBetween(from, to);
  shortestPathBetween = shortestPathBetween(from, to);

  System.out.println("Source : \n" + from + " Target : \n" + to);

  return shortestPathBetween;
}

DijsktraGraphAnalyzer.java

public class DijkstraGraphAnalyzer<N extends Node<N, E>, E extends Edge<N, E>> implements GraphAnalyzer<N, E> {

    private final Graph<N, E> graph;
    // Store the default node/distance mapping for efficiency.
    private final Map<N, Double> defaultNodeDistanceMapping;
    private final Map<N, N> defaultPreviousNodeMapping;

    public DijkstraGraphAnalyzer(final Graph<N, E> graph) {
        this.graph = graph;
        this.defaultNodeDistanceMapping = new HashMap<N, Double>();
        this.defaultPreviousNodeMapping = new HashMap<N, N>();
        for (final N n : this.graph.getNodes()) {
            this.defaultNodeDistanceMapping.put(n, Double.MAX_VALUE);
            this.defaultPreviousNodeMapping.put(n, null);
        }
    }

    @Override
    public List<N> shortestPathBetween(N from, N to) {
        final Map<N, Double> nodeDistanceMapping = buildNodeDistanceMapping(from);
        final Map<N, N> previousNodeMapping = new HashMap<N, N>(defaultPreviousNodeMapping);

        final Set<N> unsettled = new HashSet<N>();
        unsettled.add(from); 
.......

理想情况下，我希望能够将两个 MapPoint 传递到该方法中，以便它可以在各自的类中运行。

Answer 1

这里:

public <MapPoint> List<MapPoint> shortestPathBetween(MapPoint from, MapPoint to)

没有任何意义。如果 MapPoint 已经是现有类，则签名不需要任何泛型:

public List<MapPoint> shortestPathBetween(MapPoint from, MapPoint to)

如果MapPoint实际上是一个类型参数，那么你最好按照约定命名它，例如

public <T> List<T> shortestPathBetween(T from, T to)

除此之外，我建议你再回顾一下如何在Java中使用泛型，官方tutorial是一个很好的起点。