CODEWITHSUNDEEP
lambdajava-8
bp4D
bp4D

Reputation: 961

What's the elegant way to replace following code in java 8?

I have the following code in my java program (paraphrased from the actual program):

import java.util.Objects;
import java.util.function.BiPredicate;

class Class1 {
    String propertyA;
    boolean propertyANot;
    String propertyB; //Not all members have corresponding negate indicator
    String propertyC;
    String propertyD;
    boolean propertyDNot;
    ....
}


class Class2 {
    String propertyX;
    String propertyY;
    String propertyZ;
    String propertyW;
    ....
}

public class Main {

    //Fail early without inspecting all properties 
    private BiPredicate<Class1,Class2> matchObjects = (obj1,obj2) -> {

        if(obj1.propertyA != null && obj2.propertyX != null) {
            //property1Not is a boolean indicates negation
            if(obj1.propertyANot && !Objects.equals(obj1.propertyA,obj2.propertyX)) {
                return false;
            }
            else if(!obj1.propertyANot && Objects.equals(obj1.propertyA,obj2.propertyX)) {
                return false;
            }
        }

        if(obj1.propertyB != null && obj2.propertyY != null) {
            if(!Objects.equals(obj1.propertyB,obj2.propertyY)) {
                return false;
            }
        }
        .... 

        return true;
    };
}

As indicated in the comments, I want the matchObjects method to fail as soon as one of the matching conditions fail. Also the input objects don't have one-to-one correspondence to generalize the code in a loop.

I have following question:

What's the best way to rewrite this code using functional programming concepts of java8?

Having too many if conditions are making me think there is a scope for improvement here.

I also wrote a custom predicate that takes multiple & Optional parameters to generalize the testing of property equivalence in the if conditions.

However this is not helping me to get rid of multiple if conditions.

Please help & thanks in advance.

Upvotes: 1

Views: 145

Answers (1)

Donat
Donat

Reputation: 4813

You can try something like this: 

@FunctionalInterface interface TriPredicate<A, B, C> {
  boolean test (A a, B b, C c);
}

private BiPredicate<Class1, Class2> matchObjects = (obj1, obj2) -> {
  TriPredicate<String, String, Boolean> matchProp = (propA, propX, cond) ->
        propA == null && propX == null ||
        (cond == null || cond) == Objects.equals(propA, propX);
  return matchProp.test(obj1.propertyA, obj2.propertyX, obj1.propertyANot) &&
        matchProp.test(obj1.propertyB, obj2.propertyY, null) &&
        matchProp.test(obj1.propertyC, obj2.propertyZ, null) &&
        matchProp.test(obj1.propertyD, obj2.propertyW, obj1.propertyDNot);
};

Upvotes: 3

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