Predicates (Guava: Google Core Libraries for Java 23.6-jre API)

java.lang.Object
- com.google.common.base.Predicates

```
@GwtCompatible(emulated=true)
public final class Predicates
extends Object
```
Static utility methods pertaining to Predicate instances.
All methods return serializable predicates as long as they're given serializable parameters.
See the Guava User Guide article on the use of Predicate.

Since:

2.0

Author:

Kevin Bourrillion

Method Summary

All Methods Static Methods Concrete Methods Deprecated Methods
Modifier and Type	Method and Description
`static <T> Predicate<T>`	`alwaysFalse()` Returns a predicate that always evaluates to `false`.
`static <T> Predicate<T>`	`alwaysTrue()` Returns a predicate that always evaluates to `true`.
`static <T> Predicate<T>`	`and(Iterable<? extends Predicate<? super T>> components)` Returns a predicate that evaluates to `true` if each of its components evaluates to `true`.
`static <T> Predicate<T>`	`and(Predicate<? super T>... components)` Returns a predicate that evaluates to `true` if each of its components evaluates to `true`.
`static <T> Predicate<T>`	`and(Predicate<? super T> first, Predicate<? super T> second)` Returns a predicate that evaluates to `true` if both of its components evaluate to `true`.
`static Predicate<Class<?>>`	`assignableFrom(Class<?> clazz)` Deprecated. Use the correctly-named method `subtypeOf(java.lang.Class<?>)` instead. This method is scheduled to be removed in January 2018.
`static <A,B> Predicate<A>`	`compose(Predicate<B> predicate, Function<A,? extends B> function)` Returns the composition of a function and a predicate.
`static Predicate<CharSequence>`	`contains(Pattern pattern)` Returns a predicate that evaluates to `true` if the `CharSequence` being tested contains any match for the given regular expression pattern.
`static Predicate<CharSequence>`	`containsPattern(String pattern)` Returns a predicate that evaluates to `true` if the `CharSequence` being tested contains any match for the given regular expression pattern.
`static <T> Predicate<T>`	`equalTo(T target)` Returns a predicate that evaluates to `true` if the object being tested `equals()` the given target or both are null.
`static <T> Predicate<T>`	`in(Collection<? extends T> target)` Returns a predicate that evaluates to `true` if the object reference being tested is a member of the given collection.
`static Predicate<Object>`	`instanceOf(Class<?> clazz)` Returns a predicate that evaluates to `true` if the object being tested is an instance of the given class.
`static <T> Predicate<T>`	`isNull()` Returns a predicate that evaluates to `true` if the object reference being tested is null.
`static <T> Predicate<T>`	`not(Predicate<T> predicate)` Returns a predicate that evaluates to `true` if the given predicate evaluates to `false`.
`static <T> Predicate<T>`	`notNull()` Returns a predicate that evaluates to `true` if the object reference being tested is not null.
`static <T> Predicate<T>`	`or(Iterable<? extends Predicate<? super T>> components)` Returns a predicate that evaluates to `true` if any one of its components evaluates to `true`.
`static <T> Predicate<T>`	`or(Predicate<? super T>... components)` Returns a predicate that evaluates to `true` if any one of its components evaluates to `true`.
`static <T> Predicate<T>`	`or(Predicate<? super T> first, Predicate<? super T> second)` Returns a predicate that evaluates to `true` if either of its components evaluates to `true`.
`static Predicate<Class<?>>`	`subtypeOf(Class<?> clazz)` Returns a predicate that evaluates to `true` if the class being tested is assignable to (is a subtype of) `clazz`.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Method Detail
  - alwaysTrue
```
@GwtCompatible(serializable=true)
public static <T> Predicate<T> alwaysTrue()
```
    Returns a predicate that always evaluates to true.
  - alwaysFalse
```
@GwtCompatible(serializable=true)
public static <T> Predicate<T> alwaysFalse()
```
    Returns a predicate that always evaluates to false.
  - isNull
```
@GwtCompatible(serializable=true)
public static <T> Predicate<T> isNull()
```
    Returns a predicate that evaluates to true if the object reference being tested is null.
  - notNull
```
@GwtCompatible(serializable=true)
public static <T> Predicate<T> notNull()
```
    Returns a predicate that evaluates to true if the object reference being tested is not null.
  - not
```
public static <T> Predicate<T> not(Predicate<T> predicate)
```
    Returns a predicate that evaluates to true if the given predicate evaluates to false.
  - and
```
public static <T> Predicate<T> and(Iterable<? extends Predicate<? super T>> components)
```
    Returns a predicate that evaluates to true if each of its components evaluates to true. The components are evaluated in order, and evaluation will be "short-circuited" as soon as a false predicate is found. It defensively copies the iterable passed in, so future changes to it won't alter the behavior of this predicate. If components is empty, the returned predicate will always evaluate to true.
  - and
```
@SafeVarargs
public static <T> Predicate<T> and(Predicate<? super T>... components)
```
    Returns a predicate that evaluates to true if each of its components evaluates to true. The components are evaluated in order, and evaluation will be "short-circuited" as soon as a false predicate is found. It defensively copies the array passed in, so future changes to it won't alter the behavior of this predicate. If components is empty, the returned predicate will always evaluate to true.
  - and
```
public static <T> Predicate<T> and(Predicate<? super T> first,
                                   Predicate<? super T> second)
```
    Returns a predicate that evaluates to true if both of its components evaluate to true. The components are evaluated in order, and evaluation will be "short-circuited" as soon as a false predicate is found.
  - or
```
public static <T> Predicate<T> or(Iterable<? extends Predicate<? super T>> components)
```
    Returns a predicate that evaluates to true if any one of its components evaluates to true. The components are evaluated in order, and evaluation will be "short-circuited" as soon as a true predicate is found. It defensively copies the iterable passed in, so future changes to it won't alter the behavior of this predicate. If components is empty, the returned predicate will always evaluate to false.
  - or
```
@SafeVarargs
public static <T> Predicate<T> or(Predicate<? super T>... components)
```
    Returns a predicate that evaluates to true if any one of its components evaluates to true. The components are evaluated in order, and evaluation will be "short-circuited" as soon as a true predicate is found. It defensively copies the array passed in, so future changes to it won't alter the behavior of this predicate. If components is empty, the returned predicate will always evaluate to false.
  - or
```
public static <T> Predicate<T> or(Predicate<? super T> first,
                                  Predicate<? super T> second)
```
    Returns a predicate that evaluates to true if either of its components evaluates to true. The components are evaluated in order, and evaluation will be "short-circuited" as soon as a true predicate is found.
  - equalTo
```
public static <T> Predicate<T> equalTo(@NullableDecl
                                       T target)
```
    Returns a predicate that evaluates to true if the object being tested equals() the given target or both are null.
  - instanceOf
```
@GwtIncompatible
public static Predicate<Object> instanceOf(Class<?> clazz)
```
    Returns a predicate that evaluates to true if the object being tested is an instance of the given class. If the object being tested is null this predicate evaluates to false.
    If you want to filter an Iterable to narrow its type, consider using Iterables.filter(Iterable, Class) in preference.
    Warning: contrary to the typical assumptions about predicates (as documented at Predicate.apply(T)), the returned predicate may not be consistent with equals. For example, instanceOf(ArrayList.class) will yield different results for the two equal instances Lists.newArrayList(1) and Arrays.asList(1).
  - assignableFrom
```
@GwtIncompatible
 @Beta
 @Deprecated
public static Predicate<Class<?>> assignableFrom(Class<?> clazz)
```
    Deprecated. Use the correctly-named method subtypeOf(java.lang.Class<?>) instead. This method is scheduled to be removed in January 2018.
    Returns a predicate that evaluates to true if the class being tested is assignable TO clazz, that is, if it is a subtype of clazz. Yes, this method is named very incorrectly! Example:
```
 List<Class<?>> classes = Arrays.asList(
     Object.class, String.class, Number.class, Long.class);
 return Iterables.filter(classes, assignableFrom(Number.class));
 
```
    The code above returns Number.class and Long.class, not Number.class and Object.class as the name implies!
    The returned predicate does not allow null inputs.
    Since:
    
    10.0
  - subtypeOf
```
@GwtIncompatible
 @Beta
public static Predicate<Class<?>> subtypeOf(Class<?> clazz)
```
    Returns a predicate that evaluates to true if the class being tested is assignable to (is a subtype of) clazz. Example:
```
 List<Class<?>> classes = Arrays.asList(
     Object.class, String.class, Number.class, Long.class);
 return Iterables.filter(classes, subtypeOf(Number.class));
 
```
    The code above returns an iterable containing Number.class and Long.class.
    Since:
    
    20.0 (since 10.0 under the incorrect name assignableFrom)
  - in
```
public static <T> Predicate<T> in(Collection<? extends T> target)
```
    Returns a predicate that evaluates to true if the object reference being tested is a member of the given collection. It does not defensively copy the collection passed in, so future changes to it will alter the behavior of the predicate.
    This method can technically accept any Collection<?>, but using a typed collection helps prevent bugs. This approach doesn't block any potential users since it is always possible to use Predicates.<Object>in().
    
    Parameters:
    
    target - the collection that may contain the function input
  - compose
```
public static <A,B> Predicate<A> compose(Predicate<B> predicate,
                                         Function<A,? extends B> function)
```
    Returns the composition of a function and a predicate. For every x, the generated predicate returns predicate(function(x)).
    
    Returns:
    
    the composition of the provided function and predicate
  - containsPattern
```
@GwtIncompatible
public static Predicate<CharSequence> containsPattern(String pattern)
```
    Returns a predicate that evaluates to true if the CharSequence being tested contains any match for the given regular expression pattern. The test used is equivalent to Pattern.compile(pattern).matcher(arg).find()
    
    Throws:
    
    IllegalArgumentException - if the pattern is invalid
    
    Since:
    
    3.0
  - contains
```
@GwtIncompatible(value="java.util.regex.Pattern")
public static Predicate<CharSequence> contains(Pattern pattern)
```
    Returns a predicate that evaluates to true if the CharSequence being tested contains any match for the given regular expression pattern. The test used is equivalent to pattern.matcher(arg).find()
    
    Since:
    
    3.0

Class Predicates

Method Summary

Methods inherited from class java.lang.Object

Method Detail

alwaysTrue

alwaysFalse

isNull

notNull

not

and

and

and

or

or

or

equalTo

instanceOf

assignableFrom

subtypeOf

in

compose

containsPattern

contains