How to fix SonarLint: Refactor this code to use the more specialised Functional Interface 'BinaryOperator'?

Question

So im learning on how to use Lambda in Java and got the problem, that Sonar Lint is saying i should refactor the code to use the more specialised functional interface.

public float durchschnitt(float zahl1, float zahl2) {
    BiFunction<Float, Float, Float> function = (Float ersteZahl, Float zweiteZahl) -> (ersteZahl + zweiteZahl) / 2;
//  ^
//  Here I get the warning:
//  SonarLint: Refactor this code to use the more specialised Functional Interface 'BinaryOperator<Float>'
    return function.apply(zahl1, zahl2);
  }

All this little program should do is calculate the average of the two floats. The programm's working fine, but I want the warning to be gone. So how can I avoid that waring and fix the code?

Edit: I oc tried finding a solution on google etc., but found none.

score 3 · Accepted Answer · answered Jul 08 '20 at 08:52

The BinaryOperator<T> is in fact a subinterface of BiFunction<T, T, T>, and its documentation states "this is a specialization of BiFunction for the case where the operands and the result are all of the same type", so just replace with:

BinaryOperator<Float> function = (Float ersteZahl, Float zweiteZahl) -> (ersteZahl + zweiteZahl) / 2;

Also no need to declare the Float argument types, it is auto-inferred by the compiler:

BinaryOperator<Float> function = (ersteZahl, zweiteZahl) -> (ersteZahl + zweiteZahl) / 2;

How to fix SonarLint: Refactor this code to use the more specialised Functional Interface 'BinaryOperator'?

1 Answers1