[英]Trouble with Scala's class and object
我在Scala代码中找到问题时遇到问题。 任务如下。
Input: val team1: Team = new Team(8,6)
val team2: Team = new Team(6,4)
Output for 'play' method: team1.score = 4
team2.score = 0
Output for 'Winner' method: team1
任务:
创建名为“Team”的Scala类和名为“Referee”的Scala对象。
团队将:
•Int类型的状态值表示团队攻击和防御的强度,使用构造函数来设置这些值。 构造函数的参数应该是进攻然后防御
•第三个状态变量,名为Int的类型“得分”
裁判将:
•名为“play”的方法,它将两个Team对象作为参数,但不返回值。 此方法将通过将其得分设置为等于其进攻减去其他球队的防守来改变每个输入球队的状态。 如果球队的进攻小于其他球队的防守,他们的得分应为0(无负分数)
•名为“Winner”的方法,它将两个团队作为参数并返回具有较高分数的团队。 如果两个团队具有相同的分数,则返回一个新的Team对象,其中攻击和防御都设置为0
class Team(var offense: Int, var defense: Int){
var score: Int = 0 //<-Updated Variable
}
object Referee{
def play(team1: Team, team2: Team) = {
team1.score = team1.offense - team2.defense
team2.score = team2.offense - team1.defense
if (team1.offense < team2.defense){
team1.score = 0
}
else if(team2.offense < team1.defense){
team2.score = 0
}
}
def Winner(team1: Team, team2: Team) = {
if (team1.score > team2.score){
team1
}
else if(team2.score > team1.score){
team2
}
else{
new Team(0, 0)
}
}
}
分配没有返回值。 因此,您要创建一个新的Team
,并将其分配给变量p
,然后将其丢弃。
删除val p =
part。
您设置的“任务”本质上是不起作用的,因此它与Scala不相符。 只是为了好玩,这是一个更实用的方法来解决问题,避免任何可变的值:
case class Team(offense: Int, defense: Int) {
def score(other: Team): Int = Math.max(0, offense - other.defense)
}
case class TeamScore(team: Team, score: Int) {
def beats(other: TeamScore): Boolean = score > other.score
}
case class Result(score1: TeamScore, score2: TeamScore) {
def winner: Option[Team] =
if (score1 beats score2) {
Some(score1.team)
} else if (score2 beats score1) {
Some(score2.team)
} else {
None
}
}
object Referee {
def play(team1: Team, team2: Team): Result =
Result(
TeamScore(team1, team1.score(team2)),
TeamScore(team2, team2.score(team1))
)
}
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