Let’s first understand what is the meaning of the word ‘PREDICATE‘
“The term “PREDICATE” implies a statement that evaluates whether a value is true or false.”
Now let’s talk about the role of the predicate in Java 8,
- Predicate is a type of Functional interface in Java
- As mentioned, it will always return true or false
- we know that a functional interface has only one abstract method,So Predicate has one abstract method i.e. test()
- A predicate is in Java 8 and resides under java.util.function package
- Based on our requirement we can override test() method by implementing the Predicate Functional Interface
Predicate Syntax
blow is the Syntax in the Java 8
@FunctionalInterface
public interface Predicate<T> {
boolean test(T t);
}
Simple Predicate Example
this is sample program which will tell us number is positive or not
Predicate<Integer> isPositiveNo=no->no>=0;
int value= -2;
if(isPositiveNo.test(value)){
System.out.println("This is Positive No.");
}else{
System.out.println("This is Negative No.");
}
// the out put will "This is Negative No." because we have given -2 in the input