Closures Factory Example - UnquietCode/Closures-for-Java GitHub Wiki

public void factory() {
	// Closures can return other closures too, of course.
	// Here we create a closure that acts as a factory of adders.

	Closure1<Closure1<Integer, Integer>, Integer> adderFactory = new AbstractClosure1<Closure1<Integer, Integer>, Integer>() {

		public Closure1<Integer, Integer> run(Integer p1) {
			Closure1<Integer, Integer> generated = new AbstractClosure1<Integer, Integer>(p1) {

				Integer base = a1();

				public Integer run(Integer p1) {
					return base + p1;
				}
			};

			return generated;
		}
	};

	// get a few adders and try them out
	Closure1<Integer, Integer> add10 = adderFactory.run(10);
	Closure1<Integer, Integer> add5 = adderFactory.run(5);
	Closure1<Integer, Integer> sub1 = adderFactory.run(-1);

	int test = 50;
	out(add10.run(test));   // 60
	out(add5.run(test));    // 55
	out(sub1.run(test));    // 49
}

public void untypedFactory() {
	// Only the return type needs to be specified, if you're willing to keep track
	// of the necessary number of inputs and their types.

	Closure<Closure> adderFactory = new AbstractClosure<Closure>() {

		public Closure run(Object...args) {
			return new AbstractClosure<Integer>(args[0]) {
				Integer base = a1();    // this is optional, since a1() can be used directly

				public Integer run(Object...args) {
					return base + (Integer) args[0];    // we expect one argument
				}
			};
		}
	};

	// get a few adders and try them out
	Closure add10 = adderFactory.run(10);
	Closure add5 = adderFactory.run(5);
	Closure sub1 = adderFactory.run(-1);

	// you are responsible for passing in the correct number and types of arguments
	int test = 50;
	out(add10.run(test));   // 60
	out(add5.run(test));    // 55
	out(sub1.run(test));    // 40
}