Simple builder pattern for JPA predicates.

PredicateBuilder.java

package com.company.util;

import javax.persistence.criteria.CriteriaBuilder;
import javax.persistence.criteria.Path;
import javax.persistence.criteria.Predicate;
import java.util.ArrayList;
import java.util.List;

/**
 * This builder can be used to build either a conjunction or disjunction
 * predicate, where the final predicate is composed of a number of other
 * provided predicates.
 */
public class PredicateBuilder {
	private enum Type {AND, OR}
	private final List<Predicate> predicates;
	private final Type type;
	private final CriteriaBuilder criteriaBuilder;

	private PredicateBuilder(CriteriaBuilder criteriaBuilder, Type type) {
		this.predicates = new ArrayList<>();
		this.criteriaBuilder = criteriaBuilder;
		this.type = type;
	}

	public static PredicateBuilder conjunction(CriteriaBuilder criteriaBuilder) {
		return new PredicateBuilder(criteriaBuilder, Type.AND);
	}

	public static PredicateBuilder disjunction(CriteriaBuilder criteriaBuilder) {
		return new PredicateBuilder(criteriaBuilder, Type.OR);
	}

	public PredicateBuilder with(Predicate predicate) {
		this.predicates.add(predicate);
		return this;
	}

	public PredicateBuilder withLikeLowerSubstring(String s, Path<String> attributePath) {
		return this.with(this.criteriaBuilder.like(this.criteriaBuilder.lower(attributePath), "%" + s.trim().toLowerCase() + "%"));
	}

	public Predicate build() {
		Predicate[] array = this.predicates.toArray(new Predicate[0]);
		if (this.type == Type.AND) {
			return this.criteriaBuilder.and(array);
		} else {
			return this.criteriaBuilder.or(array);
		}
	}
}