EnumUtils

public class org.apache.commons.lang3.EnumUtils

Provides methods for Java enums.

#ThreadSafe#

Since:

3.0

Constructors

EnumUtils()

Deprecated. This constructor is public to permit tools that require a JavaBean instance to operate.

@Deprecated public EnumUtils()

Deprecated: TODO Make private in 4.0.

This constructor is public to permit tools that require a JavaBean instance to operate.

Methods

generateBitVector(Class, Enum[])	Creates a long bit vector representation of the given array of Enum values.
generateBitVector(Class, Iterable)	Creates a long bit vector representation of the given subset of an Enum.
generateBitVectors(Class, Enum[])	Creates a bit vector representation of the given subset of an Enum using as many longs as needed.
generateBitVectors(Class, Iterable)	Creates a bit vector representation of the given subset of an Enum using as many longs as needed.
getEnum(Class, String)	Gets the enum for the class, returning null if not found.
getEnum(Class, String, Enum)	Gets the enum for the class, returning defaultEnum if not found.
getEnumIgnoreCase(Class, String)	Gets the enum for the class, returning null if not found.
getEnumIgnoreCase(Class, String, Enum)	Gets the enum for the class, returning defaultEnum if not found.
getEnumList(Class)	Gets the List of enums.
getEnumMap(Class)	Gets the Map of enums by name.
getEnumMap(Class, Function)	Gets the Map of enums by name.
getEnumSystemProperty(Class, String, Enum)	Gets the enum for the class in a system property, returning defaultEnum if not found.
getFirstEnum(Class, int, ToIntFunction, Enum)	Gets the enum for the class and value, returning defaultEnum if not found.
getFirstEnumIgnoreCase(Class, String, Function, Enum)	Gets the enum for the class, returning defaultEnum if not found.
isValidEnum(Class, String)	Tests whether the specified name is a valid enum for the class.
isValidEnumIgnoreCase(Class, String)	Tests whether the specified name is a valid enum for the class.
processBitVector(Class, long)	Convert a long value created by EnumUtils#generateBitVector into the set of enum values that it represents.
processBitVectors(Class, long[])	Convert a long[] created by EnumUtils#generateBitVectors into the set of enum values that it represents.
stream(Class)	Returns a sequential ordered stream whose elements are the given class’ enum values.

@SafeVarargs public static <E extends Enum<E>> long generateBitVector(Class<E> enumClass, E... values)

Creates a long bit vector representation of the given array of Enum values.

This generates a value that is usable by EnumUtils#processBitVector.

Do not use this method if you have more than 64 values in your Enum, as this would create a value greater than a long can hold.

Parameters:

• enumClass – The class of the enum we are working with, not null.

• values – The values we want to convert, not null.

Type parameters:

<E> – the type of the enumeration.

Returns:

A long whose value provides a binary representation of the given set of enum values.

Throws:

• java.lang.NullPointerException – Thrown if enumClass or values is null.

• java.lang.IllegalArgumentException – Thrown if enumClass is not an enum class or has more than 64 values.

Since:

3.0.1

See also:

#generateBitVectors(Class, Iterable)

public static <E extends Enum<E>> long generateBitVector(Class<E> enumClass, Iterable<? extends E> values)

Creates a long bit vector representation of the given subset of an Enum.

This generates a value that is usable by EnumUtils#processBitVector.

Do not use this method if you have more than 64 values in your Enum, as this would create a value greater than a long can hold.

Parameters:

• enumClass – The class of the enum we are working with, not null.

• values – The values we want to convert, not null, neither containing null.

Type parameters:

<E> – the type of the enumeration.

Returns:

A long whose value provides a binary representation of the given set of enum values.

Throws:

• java.lang.NullPointerException – Thrown if enumClass or values is null.

• java.lang.IllegalArgumentException – Thrown if enumClass is not an enum class or has more than 64 values, or if any values null.

Since:

3.0.1

See also:

#generateBitVectors(Class, Iterable)

@SafeVarargs public static <E extends Enum<E>> long[] generateBitVectors(Class<E> enumClass, E... values)

Creates a bit vector representation of the given subset of an Enum using as many longs as needed.

This generates a value that is usable by EnumUtils#processBitVectors.

Use this method if you have more than 64 values in your Enum.

Parameters:

• enumClass – The class of the enum we are working with, not null.

• values – The values we want to convert, not null, neither containing null.

Type parameters:

<E> – the type of the enumeration.

Returns:

A long[] whose values provide a binary representation of the given set of enum values with the least significant digits rightmost.

Throws:

• java.lang.NullPointerException – Thrown if enumClass or values is null.

• java.lang.IllegalArgumentException – Thrown if enumClass is not an enum class, or if any values null.

Since:

3.2

public static <E extends Enum<E>> long[] generateBitVectors(Class<E> enumClass, Iterable<? extends E> values)

Creates a bit vector representation of the given subset of an Enum using as many longs as needed.

This generates a value that is usable by EnumUtils#processBitVectors.

Use this method if you have more than 64 values in your Enum.

Parameters:

• enumClass – The class of the enum we are working with, not null.

• values – The values we want to convert, not null, neither containing null.

Type parameters:

<E> – the type of the enumeration.

Returns:

A long[] whose values provide a binary representation of the given set of enum values with the least significant digits rightmost.

Throws:

• java.lang.NullPointerException – Thrown if enumClass or values is null.

• java.lang.IllegalArgumentException – Thrown if enumClass is not an enum class, or if any values null.

Since:

3.2

public static <E extends Enum<E>> E getEnum(Class<E> enumClass, String enumName)

Gets the enum for the class, returning null if not found.

This method differs from Enum#valueOf in that it does not throw an exception for an invalid enum name.

Type parameters:

<E> – The type of the enumeration.

Parameters:

• enumClass – The class of the enum to query, not null.

• enumName – The enum name, null returns null.

Returns:

The enum, null if not found.

public static <E extends Enum<E>> E getEnum(Class<E> enumClass, String enumName, E defaultEnum)

Gets the enum for the class, returning defaultEnum if not found.

This method differs from Enum#valueOf in that it does not throw an exception for an invalid enum name.

Type parameters:

<E> – The type of the enumeration.

Parameters:

• enumClass – The class of the enum to query, null returns default enum.

• enumName – The enum name, null returns default enum.

• defaultEnum – The default enum.

Returns:

The enum, default enum if not found.

Since:

3.10

public static <E extends Enum<E>> E getEnumIgnoreCase(Class<E> enumClass, String enumName)

Gets the enum for the class, returning null if not found.

This method differs from Enum#valueOf in that it does not throw an exception for an invalid enum name and performs case insensitive matching of the name.

Type parameters:

<E> – the type of the enumeration.

Parameters:

• enumClass – The class of the enum to query, may be null.

• enumName – The enum name, null returns null.

Returns:

The enum, null if not found.

Since:

3.8

public static <E extends Enum<E>> E getEnumIgnoreCase(Class<E> enumClass, String enumName, E defaultEnum)

Gets the enum for the class, returning defaultEnum if not found.

This method differs from Enum#valueOf in that it does not throw an exception for an invalid enum name and performs case insensitive matching of the name.

Type parameters:

<E> – the type of the enumeration.

Parameters:

• enumClass – The class of the enum to query, null returns default enum.

• enumName – The enum name, null returns default enum.

• defaultEnum – The default enum.

Returns:

The enum, default enum if not found.

Since:

3.10

public static <E extends Enum<E>> List<E> getEnumList(Class<E> enumClass)

Gets the List of enums.

This method is useful when you need a list of enums rather than an array.

Type parameters:

<E> – The type of the enumeration.

Parameters:

enumClass – The class of the enum to query, not null.

Returns:

The modifiable list of enums, never null.

public static <E extends Enum<E>> Map<String, E> getEnumMap(Class<E> enumClass)

Gets the Map of enums by name.

This method is useful when you need a map of enums by name.

Type parameters:

<E> – The type of the enumeration.

Parameters:

enumClass – The class of the enum to query, not null.

Returns:

The modifiable map of enum names to enums, never null.

public static <E extends Enum<E>, K> Map<K, E> getEnumMap(Class<E> enumClass, Function<E, K> keyFunction)

Gets the Map of enums by name.

This method is useful when you need a map of enums by name.

Type parameters:

• <E> – the type of enumeration.

• <K> – the type of the map key.

Parameters:

• enumClass – The class of the enum to query, not null.

• keyFunction – The function to query for the key, not null.

Returns:

The modifiable map of enums, never null.

Since:

3.13.0

public static <E extends Enum<E>> E getEnumSystemProperty(Class<E> enumClass, String propName, E defaultEnum)

Gets the enum for the class in a system property, returning defaultEnum if not found.

This method differs from Enum#valueOf in that it does not throw an exception for an invalid enum name.

If a SecurityException is caught, the return value is null.

Type parameters:

<E> – the type of the enumeration.

Parameters:

• enumClass – The class of the enum to query, not null.

• propName – The system property key for the enum name, null returns default enum.

• defaultEnum – The default enum.

Returns:

The enum, default enum if not found.

Since:

3.13.0

public static <E extends Enum<E>> E getFirstEnum(Class<E> enumClass, int value, ToIntFunction<E> toIntFunction, E defaultEnum)

Gets the enum for the class and value, returning defaultEnum if not found.

This method differs from Enum#valueOf in that it does not throw an exception for an invalid enum name and performs case insensitive matching of the name.

Type parameters:

<E> – the type of the enumeration.

Parameters:

• enumClass – The class of the enum to query, not null.

• value – The enum name, null returns default enum.

• toIntFunction – The function that gets an int for an enum for comparison to value.

• defaultEnum – The default enum.

Returns:

An enum, default enum if not found.

Since:

3.18.0

public static <E extends Enum<E>> E getFirstEnumIgnoreCase(Class<E> enumClass, String enumName, Function<E, String> stringFunction, E defaultEnum)

Gets the enum for the class, returning defaultEnum if not found.

This method differs from Enum#valueOf in that it does not throw an exception for an invalid enum name and performs case insensitive matching of the name.

Type parameters:

<E> – the type of the enumeration.

Parameters:

• enumClass – The class of the enum to query, null returns default enum.

• enumName – The enum name, null returns default enum.

• stringFunction – The function that gets the string for an enum for comparison to enumName.

• defaultEnum – The default enum.

Returns:

An enum, default enum if not found.

Since:

3.13.0

public static <E extends Enum<E>> boolean isValidEnum(Class<E> enumClass, String enumName)

Tests whether the specified name is a valid enum for the class.

This method differs from Enum#valueOf in that it checks if the name is a valid enum without needing to catch the exception.

Type parameters:

<E> – the type of the enumeration.

Parameters:

• enumClass – The class of the enum to query, null returns false.

• enumName – The enum name, null returns false.

Returns:

true if the enum name is valid, otherwise false.

public static <E extends Enum<E>> boolean isValidEnumIgnoreCase(Class<E> enumClass, String enumName)

Tests whether the specified name is a valid enum for the class.

This method differs from Enum#valueOf in that it checks if the name is a valid enum without needing to catch the exception and performs case insensitive matching of the name.

Type parameters:

<E> – the type of the enumeration.

Parameters:

• enumClass – The class of the enum to query, null returns false.

• enumName – The enum name, null returns false.

Returns:

true if the enum name is valid, otherwise false.

Since:

3.8

public static <E extends Enum<E>> EnumSet<E> processBitVector(Class<E> enumClass, long value)

Convert a long value created by EnumUtils#generateBitVector into the set of enum values that it represents.

If you store this value, beware any changes to the enum that would affect ordinal values.

Parameters:

• enumClass – The class of the enum we are working with, not null.

• value – The long value representation of a set of enum values.

Type parameters:

<E> – the type of the enumeration.

Returns:

A set of enum values.

Throws:

• java.lang.NullPointerException – Thrown if enumClass is null.

• java.lang.IllegalArgumentException – Thrown if enumClass is not an enum class or has more than 64 values.

Since:

3.0.1

public static <E extends Enum<E>> EnumSet<E> processBitVectors(Class<E> enumClass, long... values)

Convert a long[] created by EnumUtils#generateBitVectors into the set of enum values that it represents.

If you store this value, beware any changes to the enum that would affect ordinal values.

Parameters:

• enumClass – The class of the enum we are working with, not null.

• values – The long[] bearing the representation of a set of enum values, the least significant digits rightmost, not null.

Type parameters:

<E> – the type of the enumeration.

Returns:

A set of enum values.

Throws:

• java.lang.NullPointerException – Thrown if enumClass is null.

• java.lang.IllegalArgumentException – Thrown if enumClass is not an enum class.

Since:

3.2

public static <T> Stream<T> stream(Class<T> clazz)

Returns a sequential ordered stream whose elements are the given class’ enum values.

Type parameters:

<T> – the type of stream elements.

Parameters:

clazz – The class containing the enum values, may be null.

Returns:

The new stream, empty of clazz is null.

Since:

3.18.0

See also:

Class#getEnumConstants()