www.pudn.com > ThinkinginJava4thEdition(SourceCode).zip > Lunch.java

//: access/Lunch.java 
// Demonstrates class access specifiers. Make a class 
// effectively private with private constructors: 
 
class Soup1 { 
  private Soup1() {} 
  // (1) Allow creation via static method: 
  public static Soup1 makeSoup() { 
    return new Soup1(); 
  } 
} 
 
class Soup2 { 
  private Soup2() {} 
  // (2) Create a static object and return a reference 
  // upon request.(The "Singleton" pattern): 
  private static Soup2 ps1 = new Soup2(); 
  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(); 
  } 
} ///:~