the reflection mechanism is needed here: use getSubTypesOf in the Java class library reflections to get all the subclasses, but to get their corresponding objects, you need to get the MODULE$ field through getField , and you can get the corresponding objects according to this field.

package com.gcusky.util.reflect

import org.reflections.Reflections
import scala.collection.JavaConverters._

object Base {
  def subObject[T](underlying: Class[T]): Seq[T] = {
    val reflects = new Reflections("com.gcusky.util.reflect")
    reflects.getSubTypesOf(underlying).asScala.map { sub =>
      sub.getField("MODULE$").get(null).asInstanceOf[T]
    }.toSeq
  }
}

because in Scala, two class files are generated after the singleton object and the accompanying object are compiled: Base.class and Base$.class . The Base$.class class has a constant field MODULE$ , whose type is the class type of the current class Test$ .