How to negate a BiPredicate functional interface

BiPredicate is a functional interface which accepts two arguments and returns a Boolean value.

The BiPredicate interface is defined in the java.util.function package. To import the BiPredicate interface, we’ll check the following import statement:

import java.util.function.BiPredicate;

The `negate()` method

The negate() method is used to return a BiPredicate, which is a negation of the given BiPredicate.

Syntax

default BiPredicate negate()

Parameters

This method has no parameters.

Return value

This method returns a predicate.

Code

import java.util.function.BiPredicate;
public class Main{
    public static void main(String[] args) {
        BiPredicate<Integer, Integer> zeroSum = (arg1, arg2) -> arg1 + arg2 == 0;
        int arg1 = 5;
        int arg2 = -4;
        BiPredicate<Integer, Integer> notZeroSum = zeroSum.negate();
        System.out.printf("(%s + %s != 0) is %s\n", arg1, arg2, notZeroSum.test(arg1, arg2));
        arg2 = -5;
        System.out.printf("(%s + %s != 0) is %s", arg1, arg2, notZeroSum.test(arg1, arg2));
    }
}

Explanation

Line 1: We import the relevant BiPredicate interface.
Line 7: We define a BiPredicate called zeroSum to check if the sum of the arguments equals zero.
Line 9: We define the first argument called arg1.
Line 11: We define the second argument called arg2.
Line 13: We get a BiPredicate to check if the sum of the arguments is not equal to zero by negating the zeroSum BiPredicate.
Line 15: We test the negated BiPredicate using arg1 and arg2.
Line 17: We assign a different value to arg2.
Line 19: We test the composed BiPredicate using arg1 and arg2.

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