Equivalent of C# anonymous methods in Java?

Question

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(); }); 

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).

Answer 1

Pre Java 8:

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();       }    }); 

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Java 8 and above:

Java 8 adds lambda expressions to the language.

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