Enums for the win...

Scratch.java

// Gist inspired by comment to:
//
// https://medium.com/javarevisited/re-write-this-java-if-else-code-block-or-ill-reject-your-pull-request-953f20c0f544

import java.util.ArrayList;
import java.util.List;

class Scratch {

    // Sample ops and input data for demo below
    static List<Operation> ops = List.of(Operation.MULTIPLY, Operation.PLUS);
    static List<Integer> xNums = List.of(1, 22);
    static List<Integer> yNums = List.of(5, 4);


    public static void main(String[] args) {
        // Enum exmaple
        System.out.println(Operation.PLUS.perform(4, 9));


        // Accumulator for
        var resList = new ArrayList();
        for ( int i = 0; i < ops.size(); i++) {
            final int finalI = i;
            // Java streams can't stream over multiple collections (3 in this case) at the same time, unless Gathers can do that now...
            // so we iterate or the outer accumulator, and map for the enum operation.
            resList.add(ops.stream().map(operation -> (operation.perform(xNums.get(finalI), yNums.get(finalI)))).toList());
        };
        System.out.println(resList);
    }

    public enum Operation {
        PLUS,
        MINUS,
        MULTIPLY,
        DIVIDE;

        public int perform(int x, int y) {
            switch (this) {
                case PLUS:
                    return x + y;
                case MINUS:
                    return x - y;
                case MULTIPLY:
                    return x * y;
                case DIVIDE:
                    return x / y;
                default:
                    throw new RuntimeException("Bad Operator");
            }
        }
    }

}

When run you get this output:

13
[[5, 6], [88, 26]]