64 lines
1.8 KiB
Java
64 lines
1.8 KiB
Java
// functional/Factories.java
|
|
// ©2016 MindView LLC: see Copyright.txt
|
|
|
|
interface Service {
|
|
void method1();
|
|
void method2();
|
|
}
|
|
|
|
interface ServiceFactory {
|
|
Service getService();
|
|
}
|
|
|
|
class Implementation1 implements Service {
|
|
private Implementation1() {}
|
|
public void method1() { System.out.println("Implementation1 method1");}
|
|
public void method2() { System.out.println("Implementation1 method2");}
|
|
public static ServiceFactory factory =
|
|
new ServiceFactory() {
|
|
public Service getService() {
|
|
return new Implementation1();
|
|
}
|
|
};
|
|
}
|
|
|
|
class Implementation2 implements Service {
|
|
private Implementation2() {}
|
|
public void method1() { System.out.println("Implementation2 method1");}
|
|
public void method2() { System.out.println("Implementation2 method2");}
|
|
// Use method reference instead:
|
|
public static ServiceFactory factory =
|
|
Implementation2::new; // Constructor reference
|
|
}
|
|
|
|
class Implementation3 implements Service {
|
|
private Implementation3() {}
|
|
public void method1() { System.out.println("Implementation3 method1");}
|
|
public void method2() { System.out.println("Implementation3 method2");}
|
|
// Use lambda expression instead:
|
|
public static ServiceFactory factory =
|
|
() -> new Implementation3();
|
|
}
|
|
|
|
public class Factories {
|
|
public static void serviceConsumer(ServiceFactory fact) {
|
|
Service s = fact.getService();
|
|
s.method1();
|
|
s.method2();
|
|
}
|
|
public static void main(String[] args) {
|
|
serviceConsumer(Implementation1.factory);
|
|
// Implementations are completely interchangeable:
|
|
serviceConsumer(Implementation2.factory);
|
|
serviceConsumer(Implementation3.factory);
|
|
}
|
|
}
|
|
/* Output:
|
|
Implementation1 method1
|
|
Implementation1 method2
|
|
Implementation2 method1
|
|
Implementation2 method2
|
|
Implementation3 method1
|
|
Implementation3 method2
|
|
*/
|