Predicate.not() Method in Java with Examples

In order to negate an existing predicate, the Predicate.not() static method added to Java 11. The Predicate class is present in java.util.function package.

Syntax:

negate = Predicate.not( positivePredicate );

Parameters:

• Predicate whose negate is required

Return Type: Return type not() method is Predicate.

Approach:

1. Create one predicate and initialize the conditions to it.
2. Create another predicate to create negate and assign it with the not() method.

Below is the implementation of the above approach:

Java

// Implementation of Predicate.not() method in Java
import java.util.Arrays;
import java.util.List;
import java.util.function.Predicate;
import java.util.stream.Collectors;

public class GFG {
    public static void main(String[] args)
    {
        List<Integer> list
            = Arrays.asList(1, 2, 3, 4, 5, 6, 7, 8, 9, 10);

        // creating a predicate for negation
        Predicate<Integer> even = i -> i % 2 == 0;

        // creating a predicate object which
        // is negation os supplied predicate
        Predicate<Integer> odd = Predicate.not(even);

        // filtering the even number using even predicate
        List<Integer> evenNumbers
            = list.stream().filter(even).collect(
                Collectors.toList());

        // filtering the odd number using odd predicate
        List<Integer> oddNumbers
            = list.stream().filter(odd).collect(
                Collectors.toList());
        // Print the Lists
        System.out.println(evenNumbers);
        System.out.println(oddNumbers);
    }
}

Output:

[2, 4, 6, 8, 10]
[1, 3, 5, 7, 9]