Class RandomStringGenerator.Builder
- All Implemented Interfaces:
Builder<RandomStringGenerator>
- Enclosing class:
- RandomStringGenerator
public static class RandomStringGenerator.Builder extends Object implements Builder<RandomStringGenerator>
A builder for generating RandomStringGenerator
instances.
The behavior of a generator is controlled by properties set by this
builder. Each property has a default value, which can be overridden by
calling the methods defined in this class, prior to calling build()
.
All the property setting methods return the Builder
instance to allow for method chaining.
The minimum and maximum code point values are defined using withinRange(int, int)
. The
default values are 0
and Character.MAX_CODE_POINT
respectively.
The source of randomness can be set using usingRandom(TextRandomProvider)
,
otherwise ThreadLocalRandom
is used.
The type of code points returned can be filtered using filteredBy(CharacterPredicate...)
,
which defines a collection of tests that are applied to the randomly generated code points.
The code points will only be included in the result if they pass at least one of the tests.
Some commonly used predicates are provided by the CharacterPredicates
enum.
This class is not thread safe.
- Since:
- 1.1
-
Field Summary
Fields Modifier and Type Field Description static int
DEFAULT_LENGTH
The default string length produced by this builder: 0.static int
DEFAULT_MAXIMUM_CODE_POINT
The default maximum code point allowed:Character.MAX_CODE_POINT
(1114111).static int
DEFAULT_MINIMUM_CODE_POINT
The default minimum code point allowed: 0. -
Constructor Summary
Constructors Constructor Description Builder()
-
Method Summary
Modifier and Type Method Description RandomStringGenerator
build()
Builds theRandomStringGenerator
using the properties specified.RandomStringGenerator.Builder
filteredBy(CharacterPredicate... predicates)
Limits the characters in the generated string to those that match at least one of the predicates supplied.RandomStringGenerator.Builder
selectFrom(char... chars)
Limits the characters in the generated string to those who match at supplied list of Character.RandomStringGenerator.Builder
usingRandom(TextRandomProvider random)
Overrides the default source of randomness.RandomStringGenerator.Builder
withinRange(char[]... pairs)
Specifies the array of minimum and maximum char allowed in the generated string.RandomStringGenerator.Builder
withinRange(int minimumCodePoint, int maximumCodePoint)
Specifies the minimum and maximum code points allowed in the generated string.
-
Field Details
-
DEFAULT_MAXIMUM_CODE_POINT
public static final int DEFAULT_MAXIMUM_CODE_POINTThe default maximum code point allowed:Character.MAX_CODE_POINT
(1114111).- See Also:
- Constant Field Values
-
DEFAULT_LENGTH
public static final int DEFAULT_LENGTHThe default string length produced by this builder: 0.- See Also:
- Constant Field Values
-
DEFAULT_MINIMUM_CODE_POINT
public static final int DEFAULT_MINIMUM_CODE_POINTThe default minimum code point allowed: 0.- See Also:
- Constant Field Values
-
-
Constructor Details
-
Builder
public Builder()
-
-
Method Details
-
withinRange
Specifies the minimum and maximum code points allowed in the generated string.
- Parameters:
minimumCodePoint
- the smallest code point allowed (inclusive)maximumCodePoint
- the largest code point allowed (inclusive)- Returns:
this
, to allow method chaining- Throws:
IllegalArgumentException
- ifmaximumCodePoint >
Character.MAX_CODE_POINT
IllegalArgumentException
- ifminimumCodePoint < 0
IllegalArgumentException
- ifminimumCodePoint > maximumCodePoint
-
withinRange
Specifies the array of minimum and maximum char allowed in the generated string.
For example:char [][] pairs = {{'0','9'}}; char [][] pairs = {{'a','z'}}; char [][] pairs = {{'a','z'},{'0','9'}};
- Parameters:
pairs
- array of characters array, expected is to pass min, max pairs through this arg.- Returns:
this
, to allow method chaining.
-
filteredBy
Limits the characters in the generated string to those that match at least one of the predicates supplied.
Passing
null
or an empty array to this method will revert to the default behavior of allowing any character. Multiple calls to this method will replace the previously stored predicates.- Parameters:
predicates
- the predicates, may benull
or empty- Returns:
this
, to allow method chaining
-
usingRandom
Overrides the default source of randomness. It is highly recommended that a random number generator library like Apache Commons RNG be used to provide the random number generation.
When using Java 8 or later,
TextRandomProvider
is a functional interface and need not be explicitly implemented:UniformRandomProvider rng = RandomSource.create(...); RandomStringGenerator gen = new RandomStringGenerator.Builder() .usingRandom(rng::nextInt) // additional builder calls as needed .build();
Passing
null
to this method will revert to the default source of randomness.- Parameters:
random
- the source of randomness, may benull
- Returns:
this
, to allow method chaining
-
selectFrom
Limits the characters in the generated string to those who match at supplied list of Character.
Passing
null
or an empty array to this method will revert to the default behavior of allowing any character. Multiple calls to this method will replace the previously stored Character.- Parameters:
chars
- set of predefined Characters for random string generation the Character can be, may benull
or empty- Returns:
this
, to allow method chaining- Since:
- 1.2
-
build
Builds the
RandomStringGenerator
using the properties specified.- Specified by:
build
in interfaceBuilder<RandomStringGenerator>
- Returns:
- The configured
RandomStringGenerator
-