PackedInteger (Oracle Corporation - Berkeley DB Java API)
Keywords: com.sleepycat.util.PackedInteger class

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## com.sleepycat.util
Class PackedInteger

    java.lang.Object
      com.sleepycat.util.PackedInteger

    public class PackedInteger

extends Object

Static methods for reading and writing packed integers.

Note that packed integers are not sorted naturally for a byte-by-byte comparison because they have a preceding length and are little endian; therefore, they are typically not used for keys.

Values in the inclusive range [-119,119] are stored in a single byte. For values outside that range, the first byte stores the sign and the number of additional bytes. The additional bytes store (abs(value) - 119) as an unsigned little endian integer.

To read and write packed integer values, call `readInt(byte[], int)` and `writeInt(byte[], int, int)`. To get the length of a packed integer without reading it, call `getReadIntLength(byte[], int)`. To get the length of an unpacked integer without writing it, call `getWriteIntLength(int)`.

Note that the packed integer format is designed to accomodate long integers using up to 9 bytes of storage. Currently only int values are implemented, but the same format may be used in future for long values.

Field Summary
`static int` | `MAX_LENGTH` The maximum number of bytes needed to store an int value (5).

Constructor Summary
`PackedInteger()`

Method Summary
`static int` | `getReadIntLength(byte[] buf, int off)` Returns the number of bytes that would be read by `readInt(byte[], int)`.
`static int` | `getWriteIntLength(int value)` Returns the number of bytes that would be written by `writeInt(byte[], int, int)`.
`static int` | `readInt(byte[] buf, int off)` Reads a packed integer at the given buffer offset and returns it.
`static int` | `writeInt(byte[] buf, int offset, int value)` Writes a packed integer starting at the given buffer offset and returns the next offset to be written.

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

Field Detail

### MAX_LENGTH

    public static final int MAX_LENGTH

  The maximum number of bytes needed to store an int value (5). The fifth byte is only needed for values greater than (Integer.MAX_VALUE - 119) or less than (Integer.MIN_VALUE + 119).

  See Also:
    Constant Field Values

Constructor Detail

### PackedInteger

    public PackedInteger()

Method Detail

### readInt

    public static int readInt(byte[] buf,
                              int off)

  Reads a packed integer at the given buffer offset and returns it.

  Parameters:
    `buf` - the buffer to read from.
    `off` - the offset in the buffer at which to start reading.
  Returns:
    the integer that was read.

### getReadIntLength

    public static int getReadIntLength(byte[] buf,
                                       int off)

  Returns the number of bytes that would be read by `readInt(byte[], int)`.

  Parameters:
    `buf` - the buffer to read from.
    `off` - the offset in the buffer at which to start reading.
  Returns:
    the number of bytes that would be read.

### writeInt

    public static int writeInt(byte[] buf,
                               int offset,
                               int value)

  Writes a packed integer starting at the given buffer offset and returns the next offset to be written.

  Parameters:
    `buf` - the buffer to write to.
    `offset` - the offset in the buffer at which to start writing.
    `value` - the integer to be written.
  Returns:
    the offset past the bytes written.

### getWriteIntLength

    public static int getWriteIntLength(int value)

  Returns the number of bytes that would be written by `writeInt(byte[], int, int)`.

  Parameters:
    `value` - the integer to be written.
  Returns:
    the number of bytes that would be used to write the given integer.

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