Interface IdGenerator<T>

Type Parameters:

T - the type of identifier produced

Functional Interface:

This is a functional interface and can therefore be used as the assignment target for a lambda expression or method reference.

@FunctionalInterface
public interface IdGenerator<T>

Contract for generating identifiers of a particular type (for example, sequential Long values, random UUIDs, etc.)

Implementations may or may not guarantee uniqueness, ordering, or repeatability of generated identifiers. Callers should not assume any such guarantees unless documented by the implementation.

Standard implementations can be acquired via these factory methods:

• withDefaults()
• withPrefix(String)
• withRange(Long, Long)
• withRangeAndPrefix(Long, Long, String)

Author:

Mark Allen

Method Summary

Modifier and Type	Method	Description
T	generateId()	Generates an identifier.
static IdGenerator	withDefaults()	Acquires an IdGenerator with a default numeric ID range (values will wrap once maximum is reached) and a best-effort local IP prefix.
static IdGenerator	withPrefix(String prefix)	Acquires an IdGenerator with a default numeric ID range (values will wrap once maximum is reached) and the given prefix.
static IdGenerator	withRange(Long minimumId, Long maximumId)	Acquires an IdGenerator with the given minimum and maximum ID values (values will wrap once maximum is reached), and a best-effort local IP prefix.
static IdGenerator	withRangeAndPrefix(Long minimumId, Long maximumId, String prefix)	Returns a DefaultIdGenerator with the given minimum and maximum ID values (values will wrap once maximum is reached), and the specified prefix.

Method Details

generateId

@Nonnull
T generateId()

Generates an identifier.

Implementations may choose different strategies (sequential, random, host-based, etc.) and are not required to guarantee uniqueness unless explicitly documented.

Returns:

the generated identifier (never null)

withDefaults

@Nonnull
static IdGenerator withDefaults()

Acquires an IdGenerator with a default numeric ID range (values will wrap once maximum is reached) and a best-effort local IP prefix.

Callers should not rely on reference identity; this method may return a new or cached instance.

Returns:

an IdGenerator with default settings

withRange

@Nonnull
static IdGenerator withRange(@Nonnull
 Long minimumId,
 @Nonnull
 Long maximumId)

Acquires an IdGenerator with the given minimum and maximum ID values (values will wrap once maximum is reached), and a best-effort local IP prefix.

Callers should not rely on reference identity; this method may return a new or cached instance.

Parameters:

minimumId - the lowest ID that may be generated (inclusive)

maximumId - the highest ID that may be generated (inclusive)

Returns:

an IdGenerator configured with the given range

withRangeAndPrefix

@Nonnull
static IdGenerator withRangeAndPrefix(@Nonnull
 Long minimumId,
 @Nonnull
 Long maximumId,
 @Nonnull
 String prefix)

Returns a DefaultIdGenerator with the given minimum and maximum ID values (values will wrap once maximum is reached), and the specified prefix.

Callers should not rely on reference identity; this method may return a new or cached instance.

Parameters:

minimumId - the lowest ID that may be generated (inclusive)

maximumId - the highest ID that may be generated (inclusive)

prefix - a string to prepend to the generated numeric ID

Returns:

an IdGenerator configured with the given range and prefix

withPrefix

@Nonnull
static IdGenerator withPrefix(@Nonnull
 String prefix)

Acquires an IdGenerator with a default numeric ID range (values will wrap once maximum is reached) and the given prefix.

Callers should not rely on reference identity; this method may return a new or cached instance.

Parameters:

prefix - a string to prepend to the generated numeric ID

Returns:

an IdGenerator configured with the given prefix