我如何“得到"来自 Java 的 Scala 案例对象? [英] How do I "get" a Scala case object from Java?

问题描述

我在 Scala 中创建了一个 case 对象层次结构，如下所示:

I created a hierarchy of case objects in Scala that looks like the following:

package my.awesome.package

sealed abstract class PresetShapeType(val displayName: String)

case object AccelerationSensor extends PresetShapeType("Acceleration Sensor")
case object DisplacementSensor extends PresetShapeType("Displacement Sensor")
case object ForceSensor        extends PresetShapeType("Force Sensor")
case object PressureSensor     extends PresetShapeType("Pressure Sensor")
case object StrainSensor       extends PresetShapeType("Strain Sensor")

我还有一段 Java 代码，我想在其中访问 PressureSensor，但以下内容不起作用:

I also have a piece of Java code in which I'd like to access PressureSensor, but the following does not work:

package my.awesome.package.subpackage;

import my.awesome.package.PressureSensor;

// Do some stuff, then...

DVShape newshape = DVShapeFactory.createPresetShape(PressureSensor, new Point3f(0,0,0));

那么，我如何从 Java 引用 PressureSensor case 对象?我反编译了 PressureSensor 和 PressureSensor$ 类的字节码，结果如下:

So, how do I reference the PressureSensor case object from Java? I decompiled the byte code for both the PressureSensor and PressureSensor$ classes, which yielded the following:

Compiled from "DVShapeFactory.scala"
public final class org.nees.rpi.vis.PressureSensor extends java.lang.Object{
    public static final java.lang.Object productElement(int);
    public static final int productArity();
    public static final java.lang.String productPrefix();
    public static final int $tag();
    public static final java.lang.String displayName();
}

Compiled from "DVShapeFactory.scala"
public final class org.nees.rpi.vis.PressureSensor$ extends org.nees.rpi.vis.PresetShapeType implements scala.ScalaObject,scala.Product,java.io.Serializable{
    public static final org.nees.rpi.vis.PressureSensor$ MODULE$;
    public static {};
    public org.nees.rpi.vis.PressureSensor$();
    public java.lang.Object readResolve();
    public java.lang.Object productElement(int);
    public int productArity();
    public java.lang.String productPrefix();
    public final java.lang.String toString();
    public int $tag();
}

但这并没有产生任何深刻的见解.

But that didn't yield any great insight.

推荐答案

来自 Java，如:

my.awesome.package.PressureSensor$.MODULE$

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