Java.util.function.DoublePredicate interface in Java with Examples
The DoublePredicate interface was introduced in JDK 8. This interface is packaged in java.util.function package. It operates on a Double object and returns a predicate value based on a condition. It is a functional interface and thus can be used in lambda expression also.
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public interface DoublePredicate
MethodsÂ
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- test(): This function evaluates a conditional check on the double value, and returns a boolean value denoting the outcome.Â
boolean test(double value)
- and(): This function applies the AND operation on the current object and the object received as argument, and returns the newly formed predicate. This method has a default implementation.Â
default DoublePredicate and(DoublePredicate other)
- negate(): This function returns the inverse of the current predicate i.e reverses the test condition. This method has a default implementation.Â
default DoublePredicate negate()
- or(): This function applies the OR operation on the current object and the object received as argument, and returns the newly formed predicate. This method has a default implementation.Â
default DoublePredicate or(DoublePredicate other)
Example:Â Â
Java
// Java example to demonstrate DoublePredicate interfaceÂ
import java.util.function.DoublePredicate;Â
public class DoublePredicateDemo {    public static void main(String[] args)    {        // DoublePredicate to check square        // of x is less than 100        DoublePredicate db            = (x) -> { return x * x < 100.0; };        System.out.println("100 is less than 100 "                           + db.test(10));Â
        DoublePredicate db3;        // Test condition reversed        db.negate();        System.out.println("100 is greater than 100 "                           + db.test(10));Â
        DoublePredicate db2 = (x) ->        {            double y = x * x;            return y >= 36 && y < 1000;        };Â
        // Test condition ANDed        // with another predicate        db3 = db.and(db2);        System.out.println("81 is less than 100 "                           + db3.test(9));Â
        db3 = db.or(db2);        // Test condition ORed with another predicate        System.out.println("49 is greater than 36"                           + " and less than 100 "                           + db3.test(7));    }} |
Output:Â
100 is less than 100 false 100 is greater than 100 false 81 is less than 100 true 49 is greater than 36 and less than 100 true
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Reference: https://docs.oracle.com/javase/8/docs/api/java/util/function/DoublePredicate.html
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