Java IntPredicate Interface with examples

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Welcome to Java 8 Series. In this tutorial, you will learn about the Java IntPredicate Interface with examples.

IntPredicate is a Functional interface introduced as part of Java 8. It is available in java.util.function package.

What is the use of IntPredicate?

This interface is mainly used for evaluating an input of type integer and returns an output of type boolean. Consider a case where we need to write a lambda expression which accepts one input of integer type and perform an operation on the input and return a boolean.

Example

public class StaticReference {
	public static void main(String[] args) {
		Operation ops = (int input) -> {
			if (input == 10) {
				return true;
			} else
				return false;
		};
		boolean result = ops.validate(10);
		System.out.println(result);
	}

	interface Operation {
		boolean validate(int input);
	}
}

When you look at the above example, we have a function interface with an abstract method which accepts an argument of type integer return a boolean value. So a lambda expression needs a target type which needs to be a functional interface and in this example, it is Operation interface.

Instead of creating our own function interface for this scenario, Java has provided us an IntPredicate interface. Let now see in-depth details on Java IntPredicate Interface with examples.

IntPredicate Interface

@FunctionalInterface
public interface IntPredicate

IntPredicate interface contains an operation that accepts an input argument of type integer and returns a boolean value

It is a functional interface and the functional method istest(int)

Method description

boolean test(int value)
value - the input argument

Example of IntPredicate interface using lambda

public class StaticReference {
	public static void main(String[] args) {
		IntPredicate intPredicate = (int input) -> {
			if (input == 10) {
				return true;
			} else
				return false;
		};
		boolean result = intPredicate.test(10);
		System.out.println(result);
	}
}

Example of IntPredicate interface using a Method reference

public class StaticReference {
	public static void main(String[] args) {
		IntPredicate intPredicate = StaticReference::test;
		boolean result = intPredicate.test(10);
		System.out.println(result);
	}

	static boolean test(int input) {
		if (input == 10) {
			return true;
		} else
			return false;
	}
}

If you want to write a lambda expression with an input argument of type integer and boolean result, please use Java IntPredicate interface.

References

Java 8 IntPredicate official documentation

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