When a singleton object is named the same as a class, it is called a companion object. A companion object must be defined inside the same source file as the class. Let's demonstrate this with the example here:

class Animal {
  var animalName:String  = "notset"
  def setAnimalName(name: String) {
    animalName = name
  }
  def getAnimalName: String = {
    animalName
  }
  def isAnimalNameSet: Boolean = {
    if (getAnimalName == "notset") false else true
  }
}

The following is the way that you will call methods through the companion object (preferably with the same name - that is, Animal):

object Animal{
  def main(args: Array[String]): Unit= {
    val obj: Animal = new Animal
    var flag:Boolean  = false        
    obj.setAnimalName("dog")
    flag = obj.isAnimalNameSet
    println(flag)  // prints true 
             
    obj.setAnimalName("notset")
    flag = obj.isAnimalNameSet
    println(flag)   // prints false     
  }
}

A Java equivalent would be very similar, as follows:

public class Animal {
  public String animalName = "null";
  public void setAnimalName(String animalName) {
    this.animalName = animalName;
  }
  public String getAnimalName() {
    return animalName;
  }
  public boolean isAnimalNameSet() {
    if (getAnimalName() == "notset") {
      return false;
    } else {
      return true;
    }
  }

  public static void main(String[] args) {
    Animal obj = new Animal();
    boolean flag = false;         
    obj.setAnimalName("dog");
    flag = obj.isAnimalNameSet();
    System.out.println(flag);        
        
    obj.setAnimalName("notset");
    flag = obj.isAnimalNameSet();
    System.out.println(flag);
  }
}

Well done! So far, we have seen how to work with Scala objects and classes. However, working with the method for implementing and solving your data analytics problem is even more important. Thus, we will now see how to work with Scala methods in brief.

object RunAnimalExample {
  val animalObj = new Animal
  println(animalObj.getAnimalName) //prints the initial name
  println(animalObj.getAnimalAge) //prints the initial age
  // Now try setting the values of animal name and age as follows:   
  animalObj.setAnimalName("dog") //setting animal name
  animalObj.setAnaimalAge(10) //seting animal age
  println(animalObj.getAnimalName) //prints the new name of the animal 
  println(animalObj.getAnimalAge) //Prints the new age of the animal
}

The output is as follows:

notset 
-1 
dog 
10

Now, let's have a brief overview on the accessibility and the visibility of the Scala classes in the next section.