Singleton test : Singleton « Design Pattern « Java Tutorial

1. Java Tutorial
2. Design Pattern
3. Singleton

public class TestSingleton {
  public static void main(String args[]) {
    Database database;

    database = Database.getInstance("products");

    System.out.println("This is the " + database.getName() + " database.");

    database = Database.getInstance("employees");

    System.out.println("This is the " + database.getName() + " database.");
  }
}

class Database {
  private static Database singleObject;

  private int record;

  private String name;

  private Database(String n) {
    name = n;
    record = 0;
  }

  public static synchronized Database getInstance(String n) {
    if (singleObject == null) {
      singleObject = new Database(n);
    }

    return singleObject;
  }

  public void editRecord(String operation) {
    System.out.println("Performing a " + operation + " operation on record " + record
        + " in database " + name);
  }

  public String getName() {
    return name;
  }
}