Power of Reflection + Enum + Comparable to generate a simple expression evaluator

ExprEval.java

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

class AProp implements Comparable<AProp>{
	private final int a;
	public AProp(int a){
		this.a = a;
	}
	@Override
	public int compareTo(AProp other) {
		return ((Integer) a).compareTo(other.a);
	}
}

class AnAggregate{
	private final AProp a;
	public AnAggregate(AProp a){
		this.a = a;
	}
	public AProp getAProp(){ return a; }
}

enum OP{
	EQ, NE, GTE, LTE, LT, GT;
}

class SimpleExpression<E>{
	private final OP op;
	private final Method lhs_m;
	private final E rhs;
	
	public SimpleExpression(OP op, Method lhs_m, E rhs) {
		this.op    = op;
		this.lhs_m = lhs_m;
		this.rhs   = rhs;
	}
	
	public boolean eval(AnAggregate lm) throws IllegalArgumentException, IllegalAccessException, InvocationTargetException{
		Comparable<E> lhs = (Comparable<E>) lhs_m.invoke(lm);
		switch (op) {
		case EQ:
			return lhs.compareTo(rhs) == 0;
		case NE:
			return lhs.compareTo(rhs) != 0;
		case GTE:
			return lhs.compareTo(rhs) >= 0;
		case LTE:
			return lhs.compareTo(rhs) <= 0;
		case GT:
			return lhs.compareTo(rhs) > 0;
		case LT:
			return lhs.compareTo(rhs) < 0;
		}
		return false;
	}
}

class SimpleExpressionCreator{
	private final Method getAProp;
	public SimpleExpressionCreator() throws SecurityException, NoSuchMethodException{
		getAProp = AnAggregate.class.getMethod("getAProp");
	}
	public SimpleExpression<AProp> aPropCompare(OP op, AProp rhs){
		return new SimpleExpression<AProp>(op, getAProp, rhs);
	}
}

public class ExprEval{

	
	public static void main(String[] args) throws SecurityException, NoSuchMethodException, IllegalArgumentException, IllegalAccessException, InvocationTargetException {
		AnAggregate lm = new AnAggregate(new AProp(200));
		SimpleExpressionCreator sec = new SimpleExpressionCreator();
		SimpleExpression<AProp> se;
		se = sec.aPropCompare(OP.EQ, new AProp(100));
		System.out.println(se.eval(lm));
		se = sec.aPropCompare(OP.LT, new AProp(100));
		System.out.println(se.eval(lm));
		se = sec.aPropCompare(OP.GT, new AProp(100));
		System.out.println(se.eval(lm));
	}
	
}