Collector.Characteristics

AI-generated Key Takeaways

• Collector.Characteristics is an enum that provides properties for optimizing stream reduction implementations.

• It inherits methods from Enum, Object, and Comparable, offering functionalities like comparison, hash code generation, and more.

• The enum includes values like CONCURRENT, IDENTITY_FINISH, and UNORDERED, which indicate specific properties of the collector.

• CONCURRENT collectors can be used with parallel streams when the data source is unordered or the collector is also UNORDERED.

• IDENTITY_FINISH signifies that the finisher function is unnecessary and an implicit cast from the accumulator type to the result type is safe.

public static final enum Collector.Characteristics extends Enum<Collector.Characteristics>

Characteristics indicating properties of a Collector, which can be used to optimize reduction implementations.

Inherited Method Summary

From class java.lang.Enum

final Object	clone() Throws CloneNotSupportedException.
final int	compareTo(Collector.Characteristics o) Compares this enum with the specified object for order.
final boolean	equals(Object other) Returns true if the specified object is equal to this enum constant.
final void	finalize() enum classes cannot have finalize methods.
final Class<Collector.Characteristics>	getDeclaringClass() Returns the Class object corresponding to this enum constant's enum type.
final int	hashCode() Returns a hash code for this enum constant.
final String	name() Returns the name of this enum constant, exactly as declared in its enum declaration.
final int	ordinal() Returns the ordinal of this enumeration constant (its position in its enum declaration, where the initial constant is assigned an ordinal of zero).
String	toString() Returns the name of this enum constant, as contained in the declaration.
static <T extends Enum<T>> T	valueOf(Class<T> enumType, String name) Returns the enum constant of the specified enum type with the specified name.

From class java.lang.Object

Object	clone() Creates and returns a copy of this Object.
boolean	equals(Object obj) Compares this instance with the specified object and indicates if they are equal.
void	finalize() Invoked when the garbage collector has detected that this instance is no longer reachable.
final Class<?>	getClass() Returns the unique instance of Class that represents this object's class.
int	hashCode() Returns an integer hash code for this object.
final void	notify() Causes a thread which is waiting on this object's monitor (by means of calling one of the wait() methods) to be woken up.
final void	notifyAll() Causes all threads which are waiting on this object's monitor (by means of calling one of the wait() methods) to be woken up.
String	toString() Returns a string containing a concise, human-readable description of this object.
final void	wait(long timeout, int nanos) Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object or until the specified timeout expires.
final void	wait(long timeout) Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object or until the specified timeout expires.
final void	wait() Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object.

From interface java.lang.Comparable

abstract int

compareTo(Collector.Characteristics o) Compares this object with the specified object for order.

Enum Values

public static final Collector.Characteristics CONCURRENT

Indicates that this collector is concurrent, meaning that the result container can support the accumulator function being called concurrently with the same result container from multiple threads.

If a CONCURRENT collector is not also UNORDERED, then it should only be evaluated concurrently if applied to an unordered data source.

public static final Collector.Characteristics IDENTITY_FINISH

Indicates that the finisher function is the identity function and can be elided. If set, it must be the case that an unchecked cast from A to R will succeed.

public static final Collector.Characteristics UNORDERED

Indicates that the collection operation does not commit to preserving the encounter order of input elements. (This might be true if the result container has no intrinsic order, such as a Set.)