A Nonfunctional way of chaining java 8 Predicates together of different generic types.

PredicateChain.java

package com.bmchild.utils;

import java.util.Objects;
import java.util.function.Predicate;

/**
 * Non functional way of chaining predicates together
 * @author brettchild
 *
 * @param <T>
 */
public class PredicateChain<T> {
	private T objectToTest;
	private Predicate<T> predicate;
	
	public PredicateChain(T instanceToTest, Predicate<T> predicate) {
		Objects.requireNonNull(instanceToTest);
		Objects.requireNonNull(predicate);
		this.objectToTest = instanceToTest;
		this.predicate = predicate;
	}
	
	/**
	 * Private constructor to create new chains
	 * @param predicate
	 */
	private PredicateChain(Predicate<T> predicate) {
		Objects.requireNonNull(predicate);
		this.predicate = predicate;
	}
	
	public Predicate<T> toPredicate() {
		return t -> this.test();
	}
	
	public boolean test() {
		return predicate.test(objectToTest);
	}
	
	public PredicateChain<T> and(PredicateChain<?> other) {
		Objects.requireNonNull(other);
		return new PredicateChain<T>(t -> this.test() && other.test());
	}
	
	public PredicateChain<T> or(PredicateChain<?> other) {
		Objects.requireNonNull(other);
		return new PredicateChain<T>(t -> this.test() || other.test());
	}
	
	public PredicateChain<T> negate() {
		return new PredicateChain<T>(this.toPredicate().negate());
	}
	
}

PredicateChainTest.java

package com.bmchild.utils;

import org.junit.Assert;
import org.junit.Test;

public class PredicateChainTest {
	
	private String stringtoTest = "1234567890";
	private Integer inttoTest = 99;
	private Integer intTwoToTest = 5;
	
	@Test
	public void testTest() throws Exception {
		PredicateChain<String> isTenCharacters = new PredicateChain<String>(stringtoTest, t -> t.length() == 10);
		Assert.assertTrue(isTenCharacters.test());
	}
	
	@Test
	public void testAnd() throws Exception {
		PredicateChain<String> isTenCharacters = new PredicateChain<String>(stringtoTest, t -> t.length() == 10);
		PredicateChain<Integer> isLT100 = new PredicateChain<Integer>(inttoTest, i -> i < 100);
		Assert.assertTrue(isTenCharacters.and(isLT100).test());
		
		PredicateChain<Integer> isFive = new PredicateChain<Integer>(intTwoToTest, i -> i == 5);
		Assert.assertTrue(isTenCharacters.and(isLT100).and(isFive).test());
	}
	
	@Test
	public void testAnd_FALSE_STRING() throws Exception {
		PredicateChain<String> isFiveCharacters = new PredicateChain<>(stringtoTest, t -> t.length() == 5);
		PredicateChain<Integer> isLT100 = new PredicateChain<Integer>(inttoTest, i -> i < 100);
		Assert.assertFalse(isFiveCharacters.and(isLT100).test());
	}
	
	@Test
	public void testAnd_FALSE_INT() throws Exception {
		PredicateChain<String> isTenCharacters = new PredicateChain<String>(stringtoTest, t -> t.length() == 10);
		PredicateChain<Integer> isLT50 = new PredicateChain<Integer>(inttoTest, i -> i < 50);
		Assert.assertFalse(isTenCharacters.and(isLT50).test());
	}

	@Test
	public void testOr() throws Exception {
		PredicateChain<String> isTenCharacters = new PredicateChain<String>(stringtoTest, t -> t.length() == 10);
		PredicateChain<Integer> isLT100 = new PredicateChain<Integer>(inttoTest, i -> i < 100);
		Assert.assertTrue(isTenCharacters.or(isLT100).test());
	}
	
	@Test
	public void testOr_LEFT_SIDE() throws Exception {
		PredicateChain<String> isTenCharacters = new PredicateChain<String>(stringtoTest, t -> t.length() == 10);
		PredicateChain<Integer> isLt50 = new PredicateChain<Integer>(inttoTest, i -> i < 50);
		Assert.assertTrue(isTenCharacters.or(isLt50).test());
	}
	
	@Test
	public void testOr_RIGHT_SIDE() throws Exception {
		PredicateChain<String> is5Characters = new PredicateChain<String>(stringtoTest, t -> t.length() == 5);
		PredicateChain<Integer> isLt100 = new PredicateChain<Integer>(inttoTest, i -> i < 100);
		Assert.assertTrue(is5Characters.or(isLt100).test());
	}
	
	@Test
	public void testOr_NEITHER_SIDE() throws Exception {
		PredicateChain<String> is5Characters = new PredicateChain<String>(stringtoTest, t -> t.length() == 5);
		PredicateChain<Integer> isLt10 = new PredicateChain<Integer>(inttoTest, i -> i < 10);
		Assert.assertFalse(is5Characters.or(isLt10).test());
	}
	
	@Test
	public void testNegate() throws Exception {
		PredicateChain<String> isTenCharacters = new PredicateChain<String>(stringtoTest, t -> t.length() == 10).negate();
		Assert.assertFalse(isTenCharacters.test());
	}

}