如何在 Java 中使用 Scala 单例对象?

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时间:2020-10-22 04:29:54  来源:igfitidea点击:

How can I use a Scala singleton object in Java?

javascalascala-java-interop

提问by user786045

I have a Scala object that I need to use in a Java class.

我有一个需要在 Java 类中使用的 Scala 对象。

Here's the Scala object

这是 Scala 对象

object Person {
  val MALE = "m"
  val FEMALE = "f"
}

How can I use this Scala object in Java?

我如何在 Java 中使用这个 Scala 对象?

I have tried the following so far without success (compile errors):

到目前为止,我尝试了以下操作但没有成功(编译错误):

  • Person.MALE()//returns a String which is useless as I want the actual Person object
  • Person.MALE()//返回一个无用的字符串,因为我想要实际的 Person 对象

回答by Petr Pudlák

Use Person$.MODULE$. See also

使用Person$.MODULE$. 也可以看看



Edit: A working example (I checked, it compiles and works): Scala:

编辑:一个工作示例(我检查过,它编译和工作):Scala:

object Person {
  val MALE = "m";
}

Java counterpart:

Java对应:

public class Test {
    Person$ myvar = Person$.MODULE$;

    public static void main(String argv[]) {
        System.out.println(new Test().myvar.MALE());
    }
}

回答by SerCe

In case you use a package object, the access is a bit different

如果您使用 a package object,则访问有点不同

Scala:

斯卡拉:

package my.scala.package

package object Person {
  val MALE = "m";
}

Java counterpart:

Java对应:

public static void main() {
  System.out.println(my.scala.package.Person.package$.MODULE$.MALE);
}