Scala：类型不匹配；找到：所需单位：布尔值
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Scala: type mismatch; found : Unit required: Boolean
提问by Inti
Hi I'm just trying out my first bits of scala and have hit this error which I don't understand. I've been trying to work it out and have exhausted my ideas. Help?
嗨，我只是在尝试我的第一批 Scala 并遇到了这个我不明白的错误。我一直在努力解决这个问题并且已经用尽了我的想法。帮助？
scala> def calculate(count: Int) : Boolean =
| if (count<0) false
<console>:8: error: type mismatch;
found : Unit
required: Boolean
if (count<0) false
^
Thanks
谢谢
回答by dhg
You have to have an elseclause, otherwise the type checker doesn't know what the return type is when it's notthe case that count<0.
你必须有一个else条款，否则，类型检查不知道返回类型是什么，当它不是该案件count<0。
def calculate(count: Int): Boolean =
if (count<0) false
else true
Or, better yet, you don't need the if-statement at all:
或者，更好的是，您根本不需要 if 语句：
def calculate(count: Int) = count >= 0
