Java Predicate Interface

It is a functional interface which represents a predicate (boolean-valued function) of one argument. It is defined in the java.util.function package and contains test() a functional method.

Java Predicate Interface Methods

Methods	Description
boolean test(T t)	It evaluates this predicate on the given argument.
default Predicate<T> and(Predicate<? super T> other)	It returns a composed predicate that represents a short-circuiting logical AND of this predicate and another. When evaluating the composed predicate, if this predicate is false, then the other predicate is not evaluated.
default Predicate<T> negate()	It returns a predicate that represents the logical negation of this predicate.
default Predicate<T> or(Predicate<? super T> other)	It returns a composed predicate that represents a short-circuiting logical OR of this predicate and another. When evaluating the composed predicate, if this predicate is true, then the other predicate is not evaluated.
static <T> Predicate<T> isEqual(Object targetRef)	It returns a predicate that tests if two arguments are equal according to Objects.equals(Object, Object).

Java Predicate Interface Example 1

import java.util.function.Predicate;
public class PredicateInterfaceExample {
	public static void main(String[] args) {
		Predicate<Integer> pr = a -> (a > 18); // Creating predicate
		System.out.println(pr.test(10));	// Calling Predicate method  
	}
}

Output:

false

Java Predicate Interface Example 2

import java.util.function.Predicate;
public class PredicateInterfaceExample {
    static Boolean checkAge(int age){
		if(age>17)
			return true;
		else return false;
	}
    public static void main(String[] args){
    	// Using Predicate interface
    	Predicate<Integer> predicate =  PredicateInterfaceExample::checkAge;
    	// Calling Predicate method
    	boolean result = predicate.test(25);
    	System.out.println(result);
    }
}

Output: