Equivalent of C# anonymous methods in Java?
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).
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();
}
});
Java 8 and above:
Java 8 adds lambda expressions to the language.
doSomething((t) -> t + "asd");
doSomething((t) -> new StringBuilder(t).reverse().toString());
Not exactly like this but Java has something similar.
It's called anonymous inner classes.
Let me give you an example:
DoSomething(new Runnable() {
public void run() {
// "delegate" body
}
});
It's a little more verbose and requires an interface to implement, but other than that it's pretty much the same thing