等效于 Java 中的 C# 匿名方法? [英] Equivalent of C# anonymous methods in Java?

问题描述

在 C# 中，您可以匿名定义委托(即使它们只不过是语法糖).例如，我可以这样做:

In C# you can define delegates anonymously (even though they are nothing more than syntactic sugar). For example, I can do this:

public string DoSomething(Func<string, string> someDelegate)
{
     // Do something involving someDelegate(string s)
} 

DoSomething(delegate(string s){ return s += "asd"; });
DoSomething(delegate(string s){ return s.Reverse(); });

是否可以在 Java 中传递这样的代码?我正在使用处理框架，它有一个很旧的 Java 版本(它没有泛型).

Is it possible to pass code like this in Java? I'm using the processing framework, which has a quite old version of Java (it doesn't have generics).

推荐答案

Pre Java 8:

Java 最接近委托的是单方法接口.您可以使用匿名内部类.

The closest Java has to delegates are single method interfaces. You could use an anonymous inner class.

interface StringFunc {
   String func(String s);
}

void doSomething(StringFunc funk) {
   System.out.println(funk.func("whatever"));
}

doSomething(new StringFunc() {
      public String func(String s) {
           return s + "asd";
      }
   });


doSomething(new StringFunc() {
      public String func(String s) {
           return new StringBuffer(s).reverse().toString();
      }
   });

<小时>

Java 8 及更高版本:

Java 8 向该语言添加了 lambda 表达式.

Java 8 adds lambda expressions to the language.

    doSomething((t) -> t + "asd");
    doSomething((t) -> new StringBuilder(t).reverse().toString());

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