Scala and Spark for Big Data Analytics

Singleton and companion objects

In this subsection, we will see a comparative analysis between the singleton object in Scala and Java. The idea beneath the singleton pattern is to have an implementation that makes sure that only a single instance of a class can exist. Here's an example of the Singleton pattern in Java:

public class DBConnection {  private static DBConnection dbInstance;  private DBConnection() {  }  public static DBConnection getInstance() {    if (dbInstance == null) {      dbInstance = new DBConnection();    }    return dbInstance;  }}

The Scala object does a similar thing, and it's well taken care of by the compiler. Since there will be only one instance, there is no way for object creation here:

Figure 3: Object creation in Scala