RandomUtils¶

public class org.apache.commons.lang3.RandomUtils[source]¶

Supplements the standard Random class.

Use #secure() to get the singleton instance based on SecureRandom#SecureRandom() which uses a secure random number generator implementing the default random number algorithm.

Use #secureStrong() to get the singleton instance based on SecureRandom#getInstanceStrong() which uses an instance that was selected by using the algorithms/providers specified in the securerandom.strongAlgorithms Security property.

Use #insecure() to get the singleton instance based on ThreadLocalRandom#current() which is not cryptographically secure. In addition, instances do not use a cryptographically random seed unless the system property java.util.secureRandomSeed is set to true.

Starting in version 3.17.0, the method #secure() uses SecureRandom#SecureRandom() instead of SecureRandom#getInstanceStrong(), and adds #secureStrong().

Starting in version 3.16.0, this class uses #secure() for static methods and adds #insecure().

Starting in version 3.15.0, this class uses SecureRandom#getInstanceStrong() for static methods.

Before version 3.15.0, this class used ThreadLocalRandom#current() for static methods, which is not cryptographically secure.

Please note that the Apache Commons project provides a component dedicated to pseudo-random number generation, namely Commons RNG, that may be a better choice for applications with more stringent requirements (performance and/or correctness).

See also:

Since:

3.3

Constructors¶

RandomUtils()

Deprecated. RandomUtils instances should NOT be constructed in standard programming.

@Deprecated public RandomUtils()[source]¶

Deprecated: TODO Make private in 4.0.

RandomUtils instances should NOT be constructed in standard programming. Instead, the class should be used as RandomUtils.nextBytes(5);.

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

Methods¶

`insecure()`	Gets the singleton instance based on `ThreadLocalRandom#current()`; which is not cryptographically secure; for more secure processing use `#secure()` or `#secureStrong()`.
`nextBoolean()`	Deprecated. Generates a random boolean value.
`nextBytes(int)`	Deprecated. Generates an array of random bytes.
`nextDouble()`	Deprecated. Generates a random double between 0 (inclusive) and `Double#MAX_VALUE` (1.7976931348623157E308 exclusive).
`nextDouble(double, double)`	Deprecated. Generates a random double within the specified range.
`nextFloat()`	Deprecated. Generates a random float between 0 (inclusive) and `Float#MAX_VALUE` (3.4028235E38f exclusive).
`nextFloat(float, float)`	Deprecated. Generates a random float within the specified range.
`nextInt()`	Deprecated. Generates a random int between 0 (inclusive) and `Integer#MAX_VALUE` (2147483647 exclusive).
`nextInt(int, int)`	Deprecated. Generates a random integer within the specified range.
`nextLong()`	Deprecated. Generates a random long between 0 (inclusive) and `Long#MAX_VALUE` (9223372036854775807L exclusive).
`nextLong(long, long)`	Deprecated. Generates a random long within the specified range.
`randomBoolean()`	Generates a random boolean value.
`randomBytes(int)`	Generates an array of random bytes.
`randomDouble()`	Generates a random double between 0 (inclusive) and `Double#MAX_VALUE` (1.7976931348623157E308 exclusive).
`randomDouble(double, double)`	Generates a random double within the specified range.
`randomFloat()`	Generates a random float between 0 (inclusive) and Float.MAX_VALUE (exclusive).
`randomFloat(float, float)`	Generates a random float within the specified range.
`randomInt()`	Generates a random int between 0 (inclusive) and `Integer#MAX_VALUE` (2147483647 exclusive).
`randomInt(int, int)`	Generates a random integer within the specified range.
`randomLong()`	Generates a random long between 0 (inclusive) and `Long#MAX_VALUE` (9223372036854775807L, exclusive).
`randomLong(long, long)`	Generates a random long within the specified range.
`secure()`	Gets the singleton instance based on `SecureRandom#SecureRandom()` which uses the default algorithm and provider of `SecureRandom`.
`secureStrong()`	Gets the singleton instance based on `SecureRandom#getInstanceStrong()` which uses an algorithms/providers specified in the `securerandom.strongAlgorithms` `Security` property.
`toString()`

public static RandomUtils insecure()[source]¶

Gets the singleton instance based on ThreadLocalRandom#current(); which is not cryptographically secure; for more secure processing use #secure() or #secureStrong().

The method ThreadLocalRandom#current() is called on-demand.

Returns:

The singleton instance based on ThreadLocalRandom#current().

See also:

Since:

3.17.0

@Deprecated public static boolean nextBoolean()[source]¶

Deprecated: Use #secure(), #secureStrong(), or #insecure().

Generates a random boolean value.

Returns:: The random boolean.
Since:: 3.5

@Deprecated public static byte[] nextBytes(int count)[source]¶

Deprecated: Use #secure(), #secureStrong(), or #insecure().

Generates an array of random bytes.

Parameters:: count – The size of the returned array.
Returns:: The random byte array.
Throws:: java.lang.IllegalArgumentException – Thrown if count is negative.

@Deprecated public static double nextDouble()[source]¶

Deprecated: Use #secure(), #secureStrong(), or #insecure().

Generates a random double between 0 (inclusive) and Double#MAX_VALUE (1.7976931348623157E308 exclusive).

Returns:: The random double.
See also:: #nextDouble(double, double)
Since:: 3.5

@Deprecated public static double nextDouble(double startInclusive, double endExclusive)[source]¶

Deprecated: Use #secure(), #secureStrong(), or #insecure().

Generates a random double within the specified range.

Parameters:

startInclusive – The smallest value that can be returned, must be non-negative.
endExclusive – The upper bound (not included).

Throws:

java.lang.IllegalArgumentException – Thrown if startInclusive > endExclusive or if startInclusive is negative.

Returns:

The random double.

@Deprecated public static float nextFloat()[source]¶

Deprecated: Use #secure(), #secureStrong(), or #insecure().

Generates a random float between 0 (inclusive) and Float#MAX_VALUE (3.4028235E38f exclusive).

Returns:: The random float.
See also:: #nextFloat(float, float)
Since:: 3.5

@Deprecated public static float nextFloat(float startInclusive, float endExclusive)[source]¶

Deprecated: Use #secure(), #secureStrong(), or #insecure().

Generates a random float within the specified range.

Parameters:

startInclusive – The smallest value that can be returned, must be non-negative.
endExclusive – The upper bound (not included).

Throws:

java.lang.IllegalArgumentException – Thrown if startInclusive > endExclusive or if startInclusive is negative.

Returns:

The random float.

@Deprecated public static int nextInt()[source]¶

Deprecated: Use #secure(), #secureStrong(), or #insecure().

Generates a random int between 0 (inclusive) and Integer#MAX_VALUE (2147483647 exclusive).

Returns:: The random integer.
See also:: #nextInt(int, int)
Since:: 3.5

@Deprecated public static int nextInt(int startInclusive, int endExclusive)[source]¶

Deprecated: Use #secure(), #secureStrong(), or #insecure().

Generates a random integer within the specified range.

Parameters:

startInclusive – The smallest value that can be returned, must be non-negative.
endExclusive – The upper bound (not included).

Throws:

java.lang.IllegalArgumentException – Thrown if startInclusive > endExclusive or if startInclusive is negative.

Returns:

The random integer.

@Deprecated public static long nextLong()[source]¶

Deprecated: Use #secure(), #secureStrong(), or #insecure().

Generates a random long between 0 (inclusive) and Long#MAX_VALUE (9223372036854775807L exclusive).

Returns:: The random long.
See also:: #nextLong(long, long)
Since:: 3.5

@Deprecated public static long nextLong(long startInclusive, long endExclusive)[source]¶

Deprecated: Use #secure(), #secureStrong(), or #insecure().

Generates a random long within the specified range.

Parameters:

startInclusive – The smallest value that can be returned, must be non-negative.
endExclusive – The upper bound (not included).

Throws:

java.lang.IllegalArgumentException – Thrown if startInclusive > endExclusive or if startInclusive is negative.

Returns:

The random long.

public boolean randomBoolean()[source]¶

Generates a random boolean value.

Returns:: The random boolean.
Since:: 3.16.0

public byte[] randomBytes(int count)[source]¶

Generates an array of random bytes.

Parameters:: count – The size of the returned array.
Returns:: The random byte array.
Throws:: java.lang.IllegalArgumentException – Thrown if count is negative.
Since:: 3.16.0

public double randomDouble()[source]¶

Generates a random double between 0 (inclusive) and Double#MAX_VALUE (1.7976931348623157E308 exclusive).

Returns:: The random double.
See also:: #randomDouble(double, double)
Since:: 3.16.0

public double randomDouble(double startInclusive, double endExclusive)[source]¶

Generates a random double within the specified range.

Parameters:

startInclusive – The smallest value that can be returned, must be non-negative.
endExclusive – The upper bound (not included).

Throws:

java.lang.IllegalArgumentException – Thrown if startInclusive > endExclusive or if startInclusive is negative.

Returns:

The random double.

Since:

3.16.0

public float randomFloat()[source]¶

Generates a random float between 0 (inclusive) and Float.MAX_VALUE (exclusive).

Returns:: The random float.
See also:: #randomFloat(float, float)
Since:: 3.16.0

public float randomFloat(float startInclusive, float endExclusive)[source]¶

Generates a random float within the specified range.

Parameters:

startInclusive – The smallest value that can be returned, must be non-negative.
endExclusive – The upper bound (not included).

Throws:

java.lang.IllegalArgumentException – Thrown if startInclusive > endExclusive or if startInclusive is negative.

Returns:

The random float.

Since:

3.16.0

public int randomInt()[source]¶

Generates a random int between 0 (inclusive) and Integer#MAX_VALUE (2147483647 exclusive).

Returns:: The random integer.
See also:: #randomInt(int, int)
Since:: 3.16.0

public int randomInt(int startInclusive, int endExclusive)[source]¶

Generates a random integer within the specified range.

Parameters:

startInclusive – The smallest value that can be returned, must be non-negative.
endExclusive – The upper bound (not included).

Throws:

java.lang.IllegalArgumentException – Thrown if startInclusive > endExclusive or if startInclusive is negative.

Returns:

The random integer.

Since:

3.16.0

public long randomLong()[source]¶

Generates a random long between 0 (inclusive) and Long#MAX_VALUE (9223372036854775807L, exclusive).

Returns:: The random long.
See also:: #randomLong(long, long)
Since:: 3.16.0

public long randomLong(long startInclusive, long endExclusive)[source]¶

Generates a random long within the specified range.

Parameters:

startInclusive – The smallest value that can be returned, must be non-negative.
endExclusive – The upper bound (not included).

Throws:

java.lang.IllegalArgumentException – Thrown if startInclusive > endExclusive or if startInclusive is negative.

Returns:

The random long.

Since:

3.16.0

public static RandomUtils secure()[source]¶

Gets the singleton instance based on SecureRandom#SecureRandom() which uses the default algorithm and provider of SecureRandom.

The method SecureRandom#SecureRandom() is called on-demand.

Returns:: The singleton instance based on SecureRandom#SecureRandom().
See also:: SecureRandom#SecureRandom()
Since:: 3.16.0

public static RandomUtils secureStrong()[source]¶

Gets the singleton instance based on SecureRandom#getInstanceStrong() which uses an algorithms/providers specified in the securerandom.strongAlgorithms Security property.

The method SecureRandom#getInstanceStrong() is called on-demand.

Returns:: The singleton instance based on SecureRandom#getInstanceStrong().
See also:: SecureRandom#getInstanceStrong()
Since:: 3.17.0

@Override public String toString()[source]¶