OnJava8-Examples/hiding/Lunch.java

// hiding/Lunch.java
// <20>2016 MindView LLC: see Copyright.txt
// We make no guarantees that this code is fit for any purpose.
// Visit http://mindviewinc.com/Books/OnJava/ for more book information.
// Demonstrates class access specifiers. Make a class
// effectively private with private constructors:

class Soup1 {
  private Soup1() {}
  public static Soup1 makeSoup() { // (1)
    return new Soup1();
  }
}

class Soup2 {
  private Soup2() {}
  private static Soup2 ps1 = new Soup2(); // (2)
  public static Soup2 access() {
    return ps1;
  }
  public void f() {}
}

// Only one public class allowed per file:
public class Lunch {
  void testPrivate() {
    // Can't do this! Private constructor:
    //! Soup1 soup = new Soup1();
  }
  void testStatic() {
    Soup1 soup = Soup1.makeSoup();
  }
  void testSingleton() {
    Soup2.access().f();
  }
}