(run-time) Refined types in Java https://kwark.github.io/refined-in-practice/

Refined.java

import java.util.function.Predicate;

public class Refined<T> {
	
	private final T value;

	public Refined(Predicate<T> validator, T value) {
		if (validator.test(value)) {
			throw new IllegalArgumentException();
		}
		this.value = value;
	}

	
	public final T getValue() {
		return value;
	}
	
	// provide equals/hashCode/toString
}

Refining.java

import java.util.function.Predicate;

public class Refining {

	public static PositiveInt of(int value) {
		return new PositiveInt(value);
	}

	public static Age of(int value) {
		return new Age(value);
	}
	
	private static class PositiveInt extends Refined<Integer> {

		public PositiveInt(Integer value) {
			super(i -> i > 0, value);
		}
	}
	
	private static class Age extends Refined<Integer> {

		public Age(Predicate<Integer> validator, Integer value) {
			super(v -> v > 0 && v < 120, value);
		}
		
	}
	
}