在jRuby中创建接口类型的变量

Question

我想知道如何创建一个接口类型的变量并在JRuby中实现一个实现类的对象。

在Java中

目前，我们这样做

MyInterface的intrf =新的具体类（）;

如何在jRuby中执行相同的操作。我在下面做了，它会引发错误，说MyInterface方法未找到。

MyInterface intrf = ConcreteClass.new;

Answer 1

首先，MyInterface intrf = ConcreteClass.new是无效的Ruby。 MyInterface是一个常量（例如对类的常量引用，尽管它可能是对任何其他类型的引用），而不是引用的类型说明符--Ruby因此JRuby是动态类型的。其次，我假设你想编写一个JRuby类ConcreteClass，它实现了Java接口MyInterface，我在这里说的是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 

有关详细信息，请参阅JRuby wiki，尤其是页JRuby Reference。