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gnu.crypto.der
Class BitString

java.lang.Object
  extended by gnu.crypto.der.BitString
All Implemented Interfaces:
Cloneable, Comparable

public class BitString
extends Object
implements Cloneable, Comparable

Immutable representation of a bit string, which is equivalent to a byte array except some number of the rightmost bits are ignored. For example, this could be the bit string:

   00010101 11101101 11010xxx

Where the "xxx" represents three bits that should be ignored, and can have any value.

Author:
Casey Marshall (rsdio@metastatic.org)

Constructor Summary
BitString(byte[] bytes)
          Create a new bit string.
BitString(byte[] bytes, int ignoredBits)
          Create a new bit string.
BitString(byte[] bytes, int ignoredBits, boolean doShift)
          Create a new bit string, shifting the given byte array if needed.
BitString(byte[] bytes, int offset, int length)
          Create a new bit string.
BitString(byte[] bytes, int offset, int length, int ignoredBits)
          Create a new bit string.
BitString(byte[] bytes, int offset, int length, int ignoredBits, boolean doShift)
          Create a new bit string, shifting the given byte array if needed.
 
Method Summary
 Object clone()
           
 int compareTo(Object o)
           
 boolean equals(Object o)
           
 int getIgnoredBits()
          Returns the number of ignored bits.
 byte[] getShiftedByteArray()
          Returns this bit string as a byte array, with the ignored bits present.
 int size()
          Returns the size, in bits, of this bit string.
 boolean[] toBooleanArray()
          Return this bit string as a boolean array.
 byte[] toByteArray()
          Return this bit string as a byte array, with the ignored bits trimmed off.
 String toString()
           
 
Methods inherited from class java.lang.Object
finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
 

Constructor Detail

BitString

public BitString(byte[] bytes,
                 int ignoredBits,
                 boolean doShift)
Create a new bit string, shifting the given byte array if needed.

Parameters:
bytes - The byte array holding the bit string.
ignoredBits - The number of bits to ignore.
doShift - Pass true in this parameter if the byte array has not yet been shifted left by ignoredBits.
Throws:
IllegalArgumentException - If ignoredBits is negative or greater than 7.
NullPointerException - If bytes is null.

BitString

public BitString(byte[] bytes,
                 int offset,
                 int length,
                 int ignoredBits,
                 boolean doShift)
Create a new bit string, shifting the given byte array if needed.

Parameters:
bytes - The byte array holding the bit string.
offset - The offset where the meaningful bytes begin.
length - The number of meaningful bytes.
ignoredBits - The number of bits to ignore.
doShift - Pass true in this parameter if the byte array has not yet been shifted left by ignoredBits.
Throws:
IllegalArgumentException - If ignoredBits is negative or greater than 7.
NullPointerException - If bytes is null.

BitString

public BitString(byte[] bytes,
                 int offset,
                 int length,
                 int ignoredBits)
Create a new bit string.

Parameters:
bytes - The byte array holding the bit string.
offset - The offset where the meaningful bytes begin.
length - The number of meaningful bytes.
ignoredBits - The number of bits to ignore.
Throws:
IllegalArgumentException - If ignoredBits is negative or greater than 7.
NullPointerException - If bytes is null.

BitString

public BitString(byte[] bytes,
                 int ignoredBits)
Create a new bit string.

Parameters:
bytes - The byte array holding the bit string.
ignoredBits - The number of bits to ignore.
Throws:
IllegalArgumentException - If ignoredBits is negative or greater than 7.
NullPointerException - If bytes is null.

BitString

public BitString(byte[] bytes,
                 int offset,
                 int length)
Create a new bit string.

Parameters:
bytes - The byte array holding the bit string.
offset - The offset where the meaningful bytes begin.
length - The number of meaningful bytes.
Throws:
NullPointerException - If bytes is null.

BitString

public BitString(byte[] bytes)
Create a new bit string.

Parameters:
bytes - The byte array holding the bit string.
Throws:
NullPointerException - If bytes is null.
Method Detail

toByteArray

public byte[] toByteArray()
Return this bit string as a byte array, with the ignored bits trimmed off. The byte array is cloned every time this method is called to prevent modification.

Returns:
The trimmed byte array.

getShiftedByteArray

public byte[] getShiftedByteArray()
Returns this bit string as a byte array, with the ignored bits present. The byte array is cloned every time this method is called to prevent modification.

Returns:
The byte array.

getIgnoredBits

public int getIgnoredBits()
Returns the number of ignored bits.

Returns:
The number of ignored bits.

size

public int size()
Returns the size, in bits, of this bit string.

Returns:
The size of this bit string.

toBooleanArray

public boolean[] toBooleanArray()
Return this bit string as a boolean array. The value returned is of size size(), and each true value corresponding to each "1" in this bit string. The boolean array is cloned before it is returned.

Returns:
The boolean array.

clone

public Object clone()
Overrides:
clone in class Object

compareTo

public int compareTo(Object o)
Specified by:
compareTo in interface Comparable

equals

public boolean equals(Object o)
Overrides:
equals in class Object

toString

public String toString()
Overrides:
toString in class Object

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