CachedRandomBits

java.lang.Object
- org.apache.commons.lang3.CachedRandomBits

```
final class CachedRandomBits
extends java.lang.Object
```
Generates random integers of specific bit length.
It is more efficient than calling Random.nextInt(1 << nbBits). It uses a cache of cacheSize random bytes that it replenishes when it gets empty. This is especially beneficial for SecureRandom Drbg implementations, which incur a constant cost at each randomness generation.

Used internally by RandomStringUtils.

#NotThreadSafe#

- Field Summary
  
  Fields
  Modifier and Type Field Description
  
  private int bitIndex
  Index of the next bit in the cache to be used.
  
  private byte[] cache
  
  private java.util.Random random
- Constructor Summary
  
  Constructors
  Constructor Description
  
  CachedRandomBits(int cacheSize, java.util.Random random)
  Creates a new instance.
- Method Summary
  
  All Methods Instance Methods Concrete Methods
  Modifier and Type Method Description
  
  int nextBits(int bits)
  Generates a random integer with the specified number of bits.
  - Methods inherited from class java.lang.Object
    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - random
```
private final java.util.Random random
```
  - cache
```
private final byte[] cache
```
  - bitIndex
```
private int bitIndex
```
    Index of the next bit in the cache to be used.
    
    bitIndex=0 means the cache is fully random and none of the bits have been used yet.
    
    bitIndex=1 means that only the LSB of cache[0] has been used and all other bits can be used.
    
    bitIndex=8 means that only the 8 bits of cache[0] has been used.
- Constructor Detail
  - CachedRandomBits
```
CachedRandomBits(int cacheSize,
                 java.util.Random random)
```
    Creates a new instance.
    
    Parameters:
    
    cacheSize - number of bytes cached (only affects performance)
    
    random - random source
- Method Detail
  - nextBits
```
public int nextBits(int bits)
```
    Generates a random integer with the specified number of bits.
    
    Parameters:
    
    bits - number of bits to generate, MUST be between 1 and 32
    
    Returns:
    
    random integer with bits bits