Class Predicates

output/java_guava/1.4.18/Predicates.java:43–763

Static utility methods pertaining to Predicate instances. All methods returns serializable predicates as long as they're given serializable parameters. See the Guava User Guide article on the use of Predicate<

@GwtCompatible(emulated = true)
public final class Predicates {

  private Predicates() {}

  // TODO(kevinb): considering having these implement a VisitablePredicate
  // interface which specifies an accept(PredicateVisitor) method.

  /**
   * Returns a predicate that always evaluates to {@code true}.
   */

  @GwtCompatible(serializable = true)
  public static <T> Predicate<T> alwaysTrue() {
    return ObjectPredicate.ALWAYS_TRUE.withNarrowedType();
  }

  /**
   * Returns a predicate that always evaluates to {@code false}.
   */

  @GwtCompatible(serializable = true)
  public static <T> Predicate<T> alwaysFalse() {
    return ObjectPredicate.ALWAYS_FALSE.withNarrowedType();
  }

  /**
   * Returns a predicate that evaluates to {@code true} if the object reference being tested is
   * null.
   */

  @GwtCompatible(serializable = true)
  public static <T> Predicate<T> isNull() {
    return ObjectPredicate.IS_NULL.withNarrowedType();
  }

  /**
   * Returns a predicate that evaluates to {@code true} if the object reference being tested is not
   * null.
   */

  @GwtCompatible(serializable = true)
  public static <T> Predicate<T> notNull() {
    return ObjectPredicate.NOT_NULL.withNarrowedType();
  }

  /**
   * Returns a predicate that evaluates to {@code true} if the given predicate evaluates to
   * {@code false}.
   */


  public static <T> Predicate<T> not(Predicate<T> predicate) {
    return new NotPredicate<T>(predicate);
  }

  /**
   * Returns a predicate that evaluates to {@code true} if each of its components evaluates to