src/share/classes/java/util/function/Predicate.java
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rev 7675 : 8019840: Spec updates for java.util.function
Reviewed-by: mduigou
Contributed-by: brian.goetz@oracle.com
@@ -25,88 +25,95 @@
package java.util.function;
import java.util.Objects;
/**
- * Determines if the input object matches some criteria.
+ * Represents a predicate (boolean-valued function) of one argument.
*
- * @param <T> the type of argument to {@code test}
+ * <p>This is a <a href="package-summary.html">functional interface</a>
+ * whose functional method is {@link #test(Object)}.
+ *
+ * @param <T> the type of the input to the predicate
*
* @since 1.8
*/
@FunctionalInterface
public interface Predicate<T> {
/**
- * Returns {@code true} if the input object matches some criteria.
+ * Evaluates this predicate on the given argument.
*
- * @param t the input object
- * @return {@code true} if the input object matches some criteria, otherwise
- * {@code false}
+ * @param t the input argument
+ * @return {@code true} if the input argument matches the predicate,
+ * otherwise {@code false}
*/
boolean test(T t);
/**
- * Returns a predicate which evaluates to {@code true} only if this
- * predicate and the provided predicate both evaluate to {@code true}. If
- * this predicate returns {@code false} then the remaining predicate is not
- * evaluated.
- *
- * <p>Any exceptions thrown by either {@code test} method are relayed
- * to the caller; if performing first operation throws an exception, the
- * second operation will not be performed.
- *
- * @param p a predicate which will be logically-ANDed with this predicate
- * @return a new predicate which returns {@code true} only if both
- * predicates return {@code true}
- * @throws NullPointerException if p is null
- */
- default Predicate<T> and(Predicate<? super T> p) {
- Objects.requireNonNull(p);
- return (t) -> test(t) && p.test(t);
+ * Returns a composed predicate that represents a short-circuiting logical
+ * AND of this predicate and another. When evaluating the composed
+ * predicate, if this predicate is {@code false}, then the {@code other}
+ * predicate is not evaluated.
+ *
+ * <p>Any exceptions thrown during evaluation of either predicate are relayed
+ * to the caller; if evaluation of this predicate throws an exception, the
+ * {@code other} predicate will not be evaluated.
+ *
+ * @param other a predicate that will be logically-ANDed with this
+ * predicate
+ * @return a composed predicate that represents the short-circuiting logical
+ * AND of this predicate and the {@code other} predicate
+ * @throws NullPointerException if other is null
+ */
+ default Predicate<T> and(Predicate<? super T> other) {
+ Objects.requireNonNull(other);
+ return (t) -> test(t) && other.test(t);
}
/**
- * Returns a predicate which negates the result of this predicate.
- *
- * @return a new predicate who's result is always the opposite of this
+ * Returns a predicate that represents the logical negation of this
* predicate.
+ *
+ * @return a predicate that represents the logical negation of this
+ * predicate
*/
default Predicate<T> negate() {
return (t) -> !test(t);
}
/**
- * Returns a predicate which evaluates to {@code true} if either this
- * predicate or the provided predicate evaluates to {@code true}. If this
- * predicate returns {@code true} then the remaining predicate is not
- * evaluated.
- *
- * <p>Any exceptions thrown by either {@code test} method are relayed
- * to the caller; if performing first operation throws an exception, the
- * second operation will not be performed.
- *
- * @param p a predicate which will be logically-ORed with this predicate
- * @return a new predicate which returns {@code true} if either predicate
- * returns {@code true}
- * @throws NullPointerException if p is null
- */
- default Predicate<T> or(Predicate<? super T> p) {
- Objects.requireNonNull(p);
- return (t) -> test(t) || p.test(t);
+ * Returns a composed predicate that represents a short-circuiting logical
+ * OR of this predicate and another. When evaluating the composed
+ * predicate, if this predicate is {@code true}, then the {@code other}
+ * predicate is not evaluated.
+ *
+ * <p>Any exceptions thrown during evaluation of either predicate are relayed
+ * to the caller; if evaluation of this predicate throws an exception, the
+ * {@code other} predicate will not be evaluated.
+ *
+ * @param other a predicate that will be logically-ORed with this
+ * predicate
+ * @return a composed predicate that represents the short-circuiting logical
+ * OR of this predicate and the {@code other} predicate
+ * @throws NullPointerException if other is null
+ */
+ default Predicate<T> or(Predicate<? super T> other) {
+ Objects.requireNonNull(other);
+ return (t) -> test(t) || other.test(t);
}
/**
- * Returns a predicate who's result matches
- * {@code Objects.equals(target, t)}.
+ * Returns a predicate that tests if two arguments are equal according
+ * to {@link Objects#equals(Object, Object)}.
*
- * @param <T> the type of values evaluated by the predicate
- * @param target the target value to be compared for equality
- * @return a predicate who's result matches
- * {@code Objects.equals(target, t)}
+ * @param <T> the type of arguments to the predicate
+ * @param targetRef the object reference with which to compare for equality,
+ * which may be {@code null}
+ * @return a predicate that tests if two arguments are equal according
+ * to {@link Objects#equals(Object, Object)}
*/
- static <T> Predicate<T> isEqual(Object target) {
- return (null == target)
+ static <T> Predicate<T> isEqual(Object targetRef) {
+ return (null == targetRef)
? Objects::isNull
- : object -> target.equals(object);
+ : object -> targetRef.equals(object);
}
}