在jRuby中創建接口類型的變量

Question

我想知道如何創建一個接口類型的變量並在JRuby中實現一個實現類的對象。

在Java中

目前，我們這樣做

MyInterface的intrf =新的具體類（）;

如何在jRuby中執行相同的操作。我在下面做了，它會引發錯誤，說MyInterface方法未找到。

MyInterface intrf = ConcreteClass.new;

Answer 1

首先，MyInterface intrf = ConcreteClass.new是無效的Ruby。 MyInterface是一個常量（例如對類的常量引用，儘管它可能是對任何其他類型的引用），而不是引用的類型說明符--Ruby因此JRuby是動態類型的。其次，我假設你想編寫一個JRuby類ConcreteClass，它實現了Java接口MyInterface，我在這裏說的是Java包'com.example'。

require 'java' 
java_import 'com.example.MyInterface' 

class ConcreteClass 
    # Including a Java interface is the JRuby equivalent of Java's 'implements' 
    include MyInterface 

    # You now need to define methods which are equivalent to all of 
    # the methods that the interface demands. 

    # For example, let's say your interface defines a method 
    # 
    # void someMethod(String someValue) 
    # 
    # You could implements this and map it to the interface method as 
    # follows. Think of this as like an annotation on the Ruby method 
    # that tells the JRuby run-time which Java method it should be 
    # associated with. 
    java_signature 'void someMethod(java.lang.String)' 
    def some_method(some_value) 
    # Do something with some_value 
    end 

    # Implement the other interface methods... 
end 

# You can now instantiate an object which implements the Java interface 
my_interface = ConcreteClass.new 

有關詳細信息，請參閱JRuby wiki，尤其是頁JRuby Reference。