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package org.apache.commons.collections4.functors;

import java.util.Collection;

import org.apache.commons.collections4.Predicate;

Predicate implementation that returns true if only one of the predicates return true. If the array of predicates is empty, then this predicate returns false.

NOTE: In versions prior to 3.2 an array size of zero or one threw an exception.

Since:3.0
/** * Predicate implementation that returns true if only one of the * predicates return true. * If the array of predicates is empty, then this predicate returns false. * <p> * NOTE: In versions prior to 3.2 an array size of zero or one * threw an exception. * * @since 3.0 */
public final class OnePredicate<T> extends AbstractQuantifierPredicate<T> {
Serial version UID
/** Serial version UID */
private static final long serialVersionUID = -8125389089924745785L;
Factory to create the predicate.

If the array is size zero, the predicate always returns false. If the array is size one, then that predicate is returned.

Params:
  • predicates – the predicates to check, cloned, not null
Type parameters:
  • <T> – the type that the predicate queries
Throws:
Returns:the any predicate
/** * Factory to create the predicate. * <p> * If the array is size zero, the predicate always returns false. * If the array is size one, then that predicate is returned. * * @param <T> the type that the predicate queries * @param predicates the predicates to check, cloned, not null * @return the <code>any</code> predicate * @throws NullPointerException if the predicates array is null * @throws NullPointerException if any predicate in the array is null */
@SuppressWarnings("unchecked") public static <T> Predicate<T> onePredicate(final Predicate<? super T>... predicates) { FunctorUtils.validate(predicates); if (predicates.length == 0) { return FalsePredicate.<T>falsePredicate(); } if (predicates.length == 1) { return (Predicate<T>) predicates[0]; } return new OnePredicate<>(FunctorUtils.copy(predicates)); }
Factory to create the predicate.
Params:
  • predicates – the predicates to check, cloned, not null
Type parameters:
  • <T> – the type that the predicate queries
Throws:
Returns:the one predicate
/** * Factory to create the predicate. * * @param <T> the type that the predicate queries * @param predicates the predicates to check, cloned, not null * @return the <code>one</code> predicate * @throws NullPointerException if the predicates array is null * @throws NullPointerException if any predicate in the array is null */
public static <T> Predicate<T> onePredicate(final Collection<? extends Predicate<? super T>> predicates) { final Predicate<? super T>[] preds = FunctorUtils.validate(predicates); return new OnePredicate<>(preds); }
Constructor that performs no validation. Use onePredicate if you want that.
Params:
  • predicates – the predicates to check, not cloned, not null
/** * Constructor that performs no validation. * Use <code>onePredicate</code> if you want that. * * @param predicates the predicates to check, not cloned, not null */
public OnePredicate(final Predicate<? super T>... predicates) { super(predicates); }
Evaluates the predicate returning true if only one decorated predicate returns true.
Params:
  • object – the input object
Returns:true if only one decorated predicate returns true
/** * Evaluates the predicate returning true if only one decorated predicate * returns true. * * @param object the input object * @return true if only one decorated predicate returns true */
@Override public boolean evaluate(final T object) { boolean match = false; for (final Predicate<? super T> iPredicate : iPredicates) { if (iPredicate.evaluate(object)) { if (match) { return false; } match = true; } } return match; } }