Java 8 : Is it possible to assign a method reference to a variable?

Question

我用 Google 搜索了这个问题的答案，但找不到。

在 Java 8 中，我知道这是可能的:

// someMethod is defined as: someMethod(AFunctionalInterface i)
someMethod(someObject::someOtherMethod);

问题是:是否可以做到以下几点

AFunctionalInterface i = anObject::SomeMethod;

此外，是否可以将 lambda 赋值给变量并像这样传递它？

打印机 f = () -> System.out.println(..); methodThatTakesPrinter(f);

Answer 1

是的，根据 JLS 中引用的示例，这是可能的:

Task t = () -> System.out.println("hi");
Runnable r = t::invoke;

此外，声明如下:

A method reference expression is compatible in an assignment context [emphasis mine], invocation context, or casting context with a target type T if T is a functional interface type (§9.8) and the expression is congruent with the function type of the ground target type derived from T.