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Question

我需要返回一个带有Connection类的集合，但它始终返回一个错误，提示“找不到符号”。 我对如何退还款项缺乏了解。 取站的参数。

这是方法：

@Override
public Collection<Connection> getConnectionsFrom(Station station) {
    return Collection<Connection>(station);
}

这是Connection类：

public class TrainConnection implements Connection {

    double distance;

    private Map<String, Connection> connectionMap;

    public static TrainConnection newConnection = new TrainConnection();

    @Override
    public double getDistance() {
        return distance;
    }

    @Override
    public Station getStationA() {
        throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
    }

    @Override
    public Station getStationB() {
        throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
    }

    @Override
    public Station getOtherStation(Station station) {
        throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
    }

}

Answer 1

作为如何修复getConnectionsFrom的示例，假设实际上应该返回上面指出的Collection。

public Collection<Station> getConnectionsFrom(Station station)
{
   Collection<Station> connections = new ArrayList<>();
   connections.add(station);
   return connections;
}

但是，请注意，每次都会创建一个新的集合。 您需要更具体地说明您要解决的问题。