Bits

java.lang.Object
- org.jgroups.util.Bits

```
public final class Bits
extends java.lang.Object
```
Class (similar to (and partly copied from) java.nio.Bits) containing helper methods to encode variables (e.g. ints, long, List<Address> etc) to memory (byte buffer) or output streams and read variables from memory or input streams.
The write methods write a type (e.g. an int or a char) to a buffer (ByteBuffer or output stream, using variable-length encoding. If there are not enough byte in the buffer to write a type, a BufferOverflowException is thrown. If the variable cannot be written to the output stream, an IOException is thrown.
The read methods read a variable-length encoded type from a buffer or input stream. If there are fewer bytes in the buffer than needed to read the type, a BufferUnderflowException is thrown. If the read fails, an IOException is thrown.
The size() methods return the number of bytes used to encode the given type with variable-length encoding.
There are additional helper methods to write/read custom JGroups types, e.g. address lists, Views etc
Note that methods to read/write atomic types (char, int etc) should only be used if variable-length encoding is desired; otherwise DataOutput.writeInt(int) or ByteBuffer.putInt(int) should be used instead.
At the time of writing this (Feb 2014), most methods have not yet been implemented.

Since:

3.5

Author:

Bela Ban, Sanne Grinovero

Method Summary

All Methods Static Methods Concrete Methods
Modifier and Type	Method and Description
`protected static byte`	`bytesRequiredFor(int number)`
`protected static byte`	`bytesRequiredFor(long number)`
`protected static byte[]`	`decodeLength(byte len)`
`protected static byte`	`encodeLength(byte len1, byte len2)` Encodes the number of bytes needed into a single byte.
`protected static byte`	`getByteAt(long num, int index)`
`static char`	`makeChar(byte[] buf, int offset)`
`static int`	`makeInt(byte[] buf, int offset, int bytes_to_read)`
`static long`	`makeLong(byte[] buf, int offset, int bytes_to_read)`
`static short`	`makeShort(byte a)`
`static short`	`makeShort(byte a, byte b)`
`static AsciiString`	`readAsciiString(java.nio.ByteBuffer buf)` Reads an AsciiString from buf.
`static AsciiString`	`readAsciiString(java.io.DataInput in)` Reads an AsciiString from buf.
`static char`	`readChar(byte[] buf, int offset)`
`static double`	`readDouble(byte[] buf, int offset)`
`static double`	`readDouble(java.nio.ByteBuffer buf)` Reads a double from a buffer.
`static double`	`readDouble(java.io.DataInput in)` Reads a double from an input stream
`static float`	`readFloat(byte[] buf, int offset)`
`static float`	`readFloat(java.nio.ByteBuffer buf)` Reads a a float from a buffer.
`static float`	`readFloat(java.io.DataInput in)` Reads a a float from an input stream.
`static int`	`readInt(byte[] buf, int offset)`
`static int`	`readInt(java.nio.ByteBuffer buf)` Reads an int from a buffer.
`static int`	`readInt(java.io.DataInput in)` Reads an int from an input stream
`static int`	`readIntCompressed(byte[] buf, int offset)`
`static long`	`readLong(byte[] buf, int offset)`
`static long`	`readLong(java.nio.ByteBuffer buf)` Reads a long from a buffer.
`static long`	`readLong(java.io.DataInput in)` Reads a variable-length encoded long from an input stream.
`static long`	`readLongCompressed(byte[] buf, int offset)`
`static long[]`	`readLongSequence(java.nio.ByteBuffer buf)` Reads 2 compressed longs from buf.
`static long[]`	`readLongSequence(java.io.DataInput in)` Reads 2 compressed longs from in.
`static short`	`readShort(byte[] buf, int offset)`
`static java.lang.String`	`readString(java.nio.ByteBuffer buf)` Reads a string from buf.
`static java.lang.String`	`readString(java.io.DataInput in)` Reads a string from buf.
`static int`	`size(AsciiString str)` Measures the number of bytes required to encode an AsciiSring.
`static int`	`size(double num)` Computes the size of a variable-length encoded double
`static int`	`size(float num)` Computes the size of a variable-length encoded float
`static int`	`size(int num)` Computes the size of a variable-length encoded int
`static int`	`size(long num)` Computes the size of a variable-length encoded long.
`static byte`	`size(long hd, long hr)`
`static int`	`size(java.lang.String str)`
`static int`	`sizeUTF(java.lang.String str)` Measures the number of bytes required to encode a string, taking multibyte characters into account.
`static void`	`writeAsciiString(AsciiString s, java.nio.ByteBuffer buf)` Writes an AsciiString to buf.
`static void`	`writeAsciiString(AsciiString s, java.io.DataOutput out)` Writes an AsciiString to buf.
`static void`	`writeChar(char c, byte[] buf, int offset)`
`static void`	`writeDouble(double num, byte[] buf, int offset)`
`static void`	`writeDouble(double num, java.nio.ByteBuffer buf)` Writes a double to a ByteBuffer
`static void`	`writeDouble(double num, java.io.DataOutput out)` Writes a double to an output stream
`static void`	`writeFloat(float num, byte[] buf, int offset)`
`static void`	`writeFloat(float num, java.nio.ByteBuffer buf)` Writes a float to a ByteBuffer
`static void`	`writeFloat(float num, java.io.DataOutput out)` Writes a float to an output stream
`static void`	`writeInt(int num, byte[] buf, int offset)`
`static void`	`writeInt(int num, java.nio.ByteBuffer buf)` Writes an int to a ByteBuffer
`static void`	`writeInt(int num, java.io.DataOutput out)` Writes an int to an output stream
`static void`	`writeIntCompressed(int num, byte[] buf, int offset)`
`static void`	`writeLong(long num, byte[] buf, int offset)`
`static void`	`writeLong(long num, java.nio.ByteBuffer buf)` Writes a long to a ByteBuffer
`static void`	`writeLong(long num, java.io.DataOutput out)` Writes a long to out in variable-length encoding.
`static void`	`writeLongCompressed(long num, byte[] buf, int offset)`
`static void`	`writeLongSequence(long hd, long hr, java.nio.ByteBuffer buf)` Writes 2 sequence numbers (seqnos) in compressed format to buf.
`static void`	`writeLongSequence(long hd, long hr, java.io.DataOutput out)` Writes 2 sequence numbers (seqnos) in compressed format to an output stream.
`static void`	`writeShort(short s, byte[] buf, int offset)`
`static void`	`writeString(java.lang.String s, java.nio.ByteBuffer buf)` Writes a string to buf.
`static void`	`writeString(java.lang.String s, java.io.DataOutput out)` Writes a string to buf.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Method Detail
  - makeChar
```
public static char makeChar(byte[] buf,
                            int offset)
```
  - writeChar
```
public static void writeChar(char c,
                             byte[] buf,
                             int offset)
```
  - readChar
```
public static char readChar(byte[] buf,
                            int offset)
```
  - makeShort
```
public static short makeShort(byte a,
                              byte b)
```
  - makeShort
```
public static short makeShort(byte a)
```
  - writeShort
```
public static void writeShort(short s,
                              byte[] buf,
                              int offset)
```
  - readShort
```
public static short readShort(byte[] buf,
                              int offset)
```
  - writeInt
```
public static void writeInt(int num,
                            java.nio.ByteBuffer buf)
```
    Writes an int to a ByteBuffer
    
    Parameters:
    
    num - the int to be written
    
    buf - the buffer
  - writeInt
```
public static void writeInt(int num,
                            java.io.DataOutput out)
                     throws java.io.IOException
```
    Writes an int to an output stream
    
    Parameters:
    
    num - the int to be written
    
    out - the output stream
    
    Throws:
    
    java.io.IOException
  - writeInt
```
public static void writeInt(int num,
                            byte[] buf,
                            int offset)
```
  - writeIntCompressed
```
public static void writeIntCompressed(int num,
                                      byte[] buf,
                                      int offset)
```
  - readInt
```
public static int readInt(java.nio.ByteBuffer buf)
```
    Reads an int from a buffer.
    
    Parameters:
    
    buf - the buffer
    
    Returns:
    
    the int read from the buffer
  - readInt
```
public static int readInt(java.io.DataInput in)
                   throws java.io.IOException
```
    Reads an int from an input stream
    
    Parameters:
    
    in - the input stream
    
    Returns:
    
    the int read from the input stream
    
    Throws:
    
    java.io.IOException
  - readInt
```
public static int readInt(byte[] buf,
                          int offset)
```
  - readIntCompressed
```
public static int readIntCompressed(byte[] buf,
                                    int offset)
```
  - size
```
public static int size(int num)
```
    Computes the size of a variable-length encoded int
    
    Parameters:
    
    num - the int
    
    Returns:
    
    the number of bytes needed to variable-length encode num
  - writeLong
```
public static void writeLong(long num,
                             java.nio.ByteBuffer buf)
```
    Writes a long to a ByteBuffer
    
    Parameters:
    
    num - the long to be written
    
    buf - the buffer
  - writeLong
```
public static void writeLong(long num,
                             java.io.DataOutput out)
                      throws java.io.IOException
```
    Writes a long to out in variable-length encoding. Note that currently variable-length encoding is not used (a similar mechanism is used); this will be implemented later.
    
    Parameters:
    
    num - the long
    
    out - the output stream to write num to
    
    Throws:
    
    java.io.IOException
  - writeLong
```
public static void writeLong(long num,
                             byte[] buf,
                             int offset)
```
  - writeLongCompressed
```
public static void writeLongCompressed(long num,
                                       byte[] buf,
                                       int offset)
```
  - readLong
```
public static long readLong(java.nio.ByteBuffer buf)
```
    Reads a long from a buffer.
    
    Parameters:
    
    buf - the buffer
    
    Returns:
    
    the long read from the buffer
  - readLong
```
public static long readLong(java.io.DataInput in)
                     throws java.io.IOException
```
    Reads a variable-length encoded long from an input stream. Note that currently variable-length encoding is not used (a similar mechanism is used); this will be implemented later.
    
    Parameters:
    
    in - the input stream
    
    Returns:
    
    the long read from the input stream
    
    Throws:
    
    java.io.IOException
  - readLong
```
public static long readLong(byte[] buf,
                            int offset)
```
  - readLongCompressed
```
public static long readLongCompressed(byte[] buf,
                                      int offset)
```
  - size
```
public static int size(long num)
```
    Computes the size of a variable-length encoded long. Note that this is not currently using variable-length encoding (will be implemented later).
    
    Parameters:
    
    num - the long
    
    Returns:
    
    the number of bytes needed to variable-length encode num
  - writeLongSequence
```
public static void writeLongSequence(long hd,
                                     long hr,
                                     java.nio.ByteBuffer buf)
```
    Writes 2 sequence numbers (seqnos) in compressed format to buf. The seqnos are non-negative and hr is guaranteed to be >= hd.
    Once variable-length encoding has been implemented, this method will probably get dropped as we can simply write the 2 longs individually.
    
    Parameters:
    
    hd - the highest delivered seqno. Guaranteed to be a positive number
    
    hr - the highest received seqno. Guaranteed to be a positive number. Greater than or equal to hd
    
    buf - the buffer to write to
  - writeLongSequence
```
public static void writeLongSequence(long hd,
                                     long hr,
                                     java.io.DataOutput out)
                              throws java.io.IOException
```
    Writes 2 sequence numbers (seqnos) in compressed format to an output stream. The seqnos are non-negative and hr is guaranteed to be >= hd.
    Once variable-length encoding has been implemented, this method will probably get dropped as we can simply write the 2 longs individually.
    
    Parameters:
    
    hd - the highest delivered seqno. Guaranteed to be a positive number
    
    hr - the highest received seqno. Guaranteed to be a positive number. Greater than or equal to hd
    
    out - the output stream to write to
    
    Throws:
    
    java.io.IOException
  - readLongSequence
```
public static long[] readLongSequence(java.nio.ByteBuffer buf)
```
    Reads 2 compressed longs from buf.
    Once variable-length encoding has been implemented, this method will probably get dropped as we can simply read the 2 longs individually.
    
    Parameters:
    
    buf - the buffer to read from
    
    Returns:
    
    an array of 2 longs (hd and hr)
  - readLongSequence
```
public static long[] readLongSequence(java.io.DataInput in)
                               throws java.io.IOException
```
    Reads 2 compressed longs from in. Reads 2 compressed longs from buf.
    Once variable-length encoding has been implemented, this method will probably get dropped as we can simply read the 2 longs individually.
    
    Parameters:
    
    in - the input stream to read from
    
    Returns:
    
    an array of 2 longs (hd and hr)
    
    Throws:
    
    java.io.IOException
  - size
```
public static byte size(long hd,
                        long hr)
```
  - makeLong
```
public static long makeLong(byte[] buf,
                            int offset,
                            int bytes_to_read)
```
  - makeInt
```
public static int makeInt(byte[] buf,
                          int offset,
                          int bytes_to_read)
```
  - writeFloat
```
public static void writeFloat(float num,
                              java.nio.ByteBuffer buf)
```
    Writes a float to a ByteBuffer
    
    Parameters:
    
    num - the float to be written
    
    buf - the buffer
  - writeFloat
```
public static void writeFloat(float num,
                              java.io.DataOutput out)
                       throws java.io.IOException
```
    Writes a float to an output stream
    
    Parameters:
    
    num - the float to be written
    
    out - the output stream
    
    Throws:
    
    java.io.IOException
  - writeFloat
```
public static void writeFloat(float num,
                              byte[] buf,
                              int offset)
```
  - readFloat
```
public static float readFloat(java.nio.ByteBuffer buf)
```
    Reads a a float from a buffer.
    
    Parameters:
    
    buf - the buffer
    
    Returns:
    
    the float read from the buffer
  - readFloat
```
public static float readFloat(java.io.DataInput in)
                       throws java.io.IOException
```
    Reads a a float from an input stream.
    
    Parameters:
    
    in - the input stream
    
    Returns:
    
    the float read from the input stream
    
    Throws:
    
    java.io.IOException
  - readFloat
```
public static float readFloat(byte[] buf,
                              int offset)
```
  - size
```
public static int size(float num)
```
    Computes the size of a variable-length encoded float
    
    Parameters:
    
    num - the float
    
    Returns:
    
    the number of bytes needed to variable-length encode num
  - writeDouble
```
public static void writeDouble(double num,
                               java.nio.ByteBuffer buf)
```
    Writes a double to a ByteBuffer
    
    Parameters:
    
    num - the double to be written
    
    buf - the buffer
  - writeDouble
```
public static void writeDouble(double num,
                               java.io.DataOutput out)
                        throws java.io.IOException
```
    Writes a double to an output stream
    
    Parameters:
    
    num - the double to be written
    
    out - the output stream
    
    Throws:
    
    java.io.IOException
  - writeDouble
```
public static void writeDouble(double num,
                               byte[] buf,
                               int offset)
```
  - readDouble
```
public static double readDouble(java.nio.ByteBuffer buf)
```
    Reads a double from a buffer.
    
    Parameters:
    
    buf - the buffer
    
    Returns:
    
    the double read from the buffer
  - readDouble
```
public static double readDouble(java.io.DataInput in)
                         throws java.io.IOException
```
    Reads a double from an input stream
    
    Parameters:
    
    in - the input stream
    
    Returns:
    
    the double read from the input stream
    
    Throws:
    
    java.io.IOException
  - readDouble
```
public static double readDouble(byte[] buf,
                                int offset)
```
  - size
```
public static int size(double num)
```
    Computes the size of a variable-length encoded double
    
    Parameters:
    
    num - the double
    
    Returns:
    
    the number of bytes needed to variable-length encode num
  - writeString
```
public static void writeString(java.lang.String s,
                               java.nio.ByteBuffer buf)
```
    Writes a string to buf. The length of the string is written first, followed by the chars (as single-byte values). Multi-byte values are truncated: only the lower byte of each multi-byte char is written, similar to DataOutput.writeChars(String).
    
    Parameters:
    
    s - the string
    
    buf - the buffer
  - writeString
```
public static void writeString(java.lang.String s,
                               java.io.DataOutput out)
                        throws java.io.IOException
```
    Writes a string to buf. The length of the string is written first, followed by the chars (as single-byte values). Multi-byte values are truncated: only the lower byte of each multi-byte char is written, similar to DataOutput.writeChars(String).
    
    Parameters:
    
    s - the string
    
    out - the output stream
    
    Throws:
    
    java.io.IOException
  - readString
```
public static java.lang.String readString(java.nio.ByteBuffer buf)
```
    Reads a string from buf. The length is read first, followed by the chars. Each char is a single byte
    
    Parameters:
    
    buf - the buffer
    
    Returns:
    
    the string read from buf
  - readString
```
public static java.lang.String readString(java.io.DataInput in)
                                   throws java.io.IOException
```
    Reads a string from buf. The length is read first, followed by the chars. Each char is a single byte
    
    Parameters:
    
    in - the input stream
    
    Returns:
    
    the string read from buf
    
    Throws:
    
    java.io.IOException
  - sizeUTF
```
public static int sizeUTF(java.lang.String str)
```
    Measures the number of bytes required to encode a string, taking multibyte characters into account. Measures strings written by DataOutput.writeUTF(String).
    
    Parameters:
    
    str - the string
    
    Returns:
    
    the number of bytes required for encoding str
  - size
```
public static int size(java.lang.String str)
```
  - writeAsciiString
```
public static void writeAsciiString(AsciiString s,
                                    java.nio.ByteBuffer buf)
```
    Writes an AsciiString to buf. The length of the string is written first, followed by the chars (as single-byte values).
    
    Parameters:
    
    s - the string
    
    buf - the buffer
  - writeAsciiString
```
public static void writeAsciiString(AsciiString s,
                                    java.io.DataOutput out)
                             throws java.io.IOException
```
    Writes an AsciiString to buf. The length of the string is written first, followed by the chars (as single-byte values).
    
    Parameters:
    
    s - the string
    
    out - the output stream
    
    Throws:
    
    java.io.IOException
  - readAsciiString
```
public static AsciiString readAsciiString(java.nio.ByteBuffer buf)
```
    Reads an AsciiString from buf. The length is read first, followed by the chars. Each char is a single byte
    
    Parameters:
    
    buf - the buffer
    
    Returns:
    
    the string read from buf
  - readAsciiString
```
public static AsciiString readAsciiString(java.io.DataInput in)
                                   throws java.io.IOException
```
    Reads an AsciiString from buf. The length is read first, followed by the chars. Each char is a single byte
    
    Parameters:
    
    in - the input stream
    
    Returns:
    
    the string read from buf
    
    Throws:
    
    java.io.IOException
  - size
```
public static int size(AsciiString str)
```
    Measures the number of bytes required to encode an AsciiSring.
    
    Parameters:
    
    str - the string
    
    Returns:
    
    the number of bytes required for encoding str
  - encodeLength
```
protected static byte encodeLength(byte len1,
                                   byte len2)
```
    Encodes the number of bytes needed into a single byte. The first number is encoded in the first nibble (the first 4 bits), the second number in the second nibble
    
    Parameters:
    
    len1 - The number of bytes needed to store a long. Must be between 0 and 8
    
    len2 - The number of bytes needed to store a long. Must be between 0 and 8
    
    Returns:
    
    The byte storing the 2 numbers len1 and len2
  - decodeLength
```
protected static byte[] decodeLength(byte len)
```
  - bytesRequiredFor
```
protected static byte bytesRequiredFor(long number)
```
  - bytesRequiredFor
```
protected static byte bytesRequiredFor(int number)
```
  - getByteAt
```
protected static byte getByteAt(long num,
                                int index)
```

Class Bits

Method Summary

Methods inherited from class java.lang.Object

Method Detail

makeChar

writeChar

readChar

makeShort

makeShort

writeShort

readShort

writeInt

writeInt

writeInt

writeIntCompressed

readInt

readInt

readInt

readIntCompressed

size

writeLong

writeLong

writeLong

writeLongCompressed

readLong

readLong

readLong

readLongCompressed

size

writeLongSequence

writeLongSequence

readLongSequence

readLongSequence

size

makeLong

makeInt

writeFloat

writeFloat

writeFloat

readFloat

readFloat

readFloat

size

writeDouble

writeDouble

writeDouble

readDouble

readDouble

readDouble

size

writeString

writeString

readString

readString

sizeUTF

size

writeAsciiString

writeAsciiString

readAsciiString

readAsciiString

size

encodeLength

decodeLength

bytesRequiredFor

bytesRequiredFor

getByteAt