覆盖 Scala 枚举中的 toString 方法
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Overriding toString method in Scala Enumeration
提问by Suheil
How can I override "toString" to make this Scala code acts like the following Java code.
如何覆盖“toString”以使此 Scala 代码的行为类似于以下 Java 代码。
Code in Scala
Scala 中的代码
object BIT extends Enumeration {
type BIT = Value
val ZERO, ONE, ANY = Value
override def toString() =
this match {
case ANY => "x "
case ZERO=> "0 "
case ONE => "1 "
}
}
val b = ONE
println(ONE) // returns ONE
Wanted toString behaviour should produce same output as the following Java code.
想要的 toString 行为应该产生与以下 Java 代码相同的输出。
public enum BIT {
ZERO, ONE, ANY;
/** print BIT as 0,1, and X */
public String toString() {
switch (this) {
case ZERO:
return "0 ";
case ONE:
return "1 ";
default://ANY
return "X ";
}
}
}
BIT b = ONE;
System.out.println(b); // returns 1
I think I am overriding the wrong "toString" method.
我想我覆盖了错误的“toString”方法。
回答by Dan Simon
First, yes you are overriding the wrong toString method. You're overriding the method on the BITobject itself, which is not very useful.
首先，是的，您覆盖了错误的 toString 方法。您正在覆盖BIT对象本身的方法，这不是很有用。
Second, you do this much easier by simply doing
其次，你只需简单地做这件事就容易多了
object BIT extends Enumeration {
type BIT = Value
val ZERO = Value("0")
val ONE = Value("1")
val ANY = Value("x")
}
Then you can do
然后你可以做
println(BIT.ONE) //prints "1"
回答by lockwobr
If you want to set the value and the string you can do it like this:
如果你想设置值和字符串，你可以这样做：
scala> object BIT extends Enumeration {
| type BIT = Value
| val ZERO = Value(0, "0")
| val ONE = Value(1, "1")
| val ANY = Value("x")
| }
defined module BIT
scala> BIT.ZERO.toString
res2: String = 0
scala> BIT.ZERO.id
res3: Int = 0
scala> BIT.ANY.id
res4: Int = 2
scala> BIT.ANY.toString
res5: String = x
