Is there a data structure for storing boolean expressions?

Question

I need to store Boolean expressions like this:

x1 AND x2 AND x3 OR (x4 AND x5) AND (NOT x6)

Each x variable is a Boolean expression like == or != with values. The problem is to store nested AND and OR clauses (inside themselves and/or inside each other) and wrap them with NOT. The wrapping depth can be very deep.

Does the Java SDK have data structure for these expressions?

Answer 1

In Java 8 the functional interface Predicate<T> is the way to go.

Here are the Java docs.

And here are various examples.

So in your use case it will be something as follows:

public static Predicate<Integer> equals(Integer compare) {
    return i -> i.equals(compare);
}

public static Predicate<Integer> complex() {
    return equals(1).and(equals(2)).and(equals(3)).or(equals(4).and(equals(5))).and(equals(6).negate());
}

Remember — only Java 8 onwards!