Enum abrastract method

gistfile1.txt

class ArithmeticFunction {

	private static enum Operation {
		add {
			@Override
			int apply(int a, int b) {
				return a + b;
			}
		}, subtract {
			@Override
			int apply(int a, int b) {
				return a - b;
			}
		}, multiply {
			@Override
			int apply(int a, int b) {
				return a * b;
			}
		}, divide {
			@Override
			int apply(int a, int b) {
				return a / b;
			}
		};

		abstract int apply(int a, int b);
	}

	public static int arithmetic(int a, int b, String operator) {
		return Operation.valueOf(operator).apply(a, b);
	}
}