Question

我有一个模拟国际象棋游戏的模块，有以下两个类：

case class Pos(x: Char, y: Char)
abstract class Piece(player: Int, pos: Pos)

我有一套Piece：

val pieces: Set[Piece]

我想像这样过滤它：

pieces.filter(piece => !(piece.pos == pos2))

但是，我收到此错误：

Error:(45, 36) value pos is not a member of chess.Piece
    pieces.filter(piece => !(piece.pos == pos2))
                               ^

为什么会这样？我是否可以使用Piece引用.pos类型的变量？

Answer 1

这是因为没有为你的Piece类设置getter。

// No getters/setters created
abstract class Piece(player: Int, pos: Pos) 

// Only Getters created because constructor params are immutable 
abstract class Piece(val player: Int, val pos: Pos) 

// Both Getters & Setter created because constructor params are mutable 
abstract class Piece(var player: Int, var pos: Pos)

按字段解决案例

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