Class ArrayIntCompressed


  • public class ArrayIntCompressed
    extends Object
    This class compresses fixed-size int[] in a very fast and memory efficient manner if many leading and/or trailing bits of the stored ints are not used commonly. The internal data is never copied during the process of retrieving or reconstructing objects of this class and allows for fast I/O writing and reading of the underlying byte[]. Furthermore almost no additional data is used beside the underlying byte[]. Thereby the memory consumption of this data structure is kept at a minimum to build efficient int[] caches.
    • Constructor Summary

      Constructors 
      Constructor Description
      ArrayIntCompressed​(byte[] bytes)
      Create IntArrayCompressed from bytes formerly got from toByteArray().
      ArrayIntCompressed​(int[] ints)
      Create IntArrayCompressed from ints representing the data to be stored in compressed form.
      ArrayIntCompressed​(int[] ints, int offset, int length)
      Create IntArrayCompressed from ints representing the data to be stored in compressed form (from offset to offset+length).
      ArrayIntCompressed​(int size, int leadingClearBits, int trailingClearBits)
      Create IntArrayCompressed from number of ints to be stored, the number of leading and trailing clear bits.
    • Constructor Detail

      • ArrayIntCompressed

        public ArrayIntCompressed​(byte[] bytes)
        Create IntArrayCompressed from bytes formerly got from toByteArray().
        Parameters:
        bytes - bytes formerly got from toByteArray()
      • ArrayIntCompressed

        public ArrayIntCompressed​(int size,
                                  int leadingClearBits,
                                  int trailingClearBits)
        Create IntArrayCompressed from number of ints to be stored, the number of leading and trailing clear bits. Everything else is stored in the internal data structure.
        Parameters:
        size - number of ints to be stored
        leadingClearBits - number of leading clear bits
        trailingClearBits - number of trailing clear bits
      • ArrayIntCompressed

        public ArrayIntCompressed​(int[] ints)
        Create IntArrayCompressed from ints representing the data to be stored in compressed form.
        Parameters:
        ints - ints representing the data to be stored in compressed form
      • ArrayIntCompressed

        public ArrayIntCompressed​(int[] ints,
                                  int offset,
                                  int length)
        Create IntArrayCompressed from ints representing the data to be stored in compressed form (from offset to offset+length).
        Parameters:
        ints - ints representing the data to be stored in compressed form
        offset - offset from which on to compress the ints
        length - number of ints to compress from the given array
    • Method Detail

      • set

        public void set​(int index,
                        int value)
        Set value at the given index.
        Parameters:
        index - index at which the value should be set
        value - value to be set at the given index
      • get

        public int get​(int index)
        Get value from the given index.
        Parameters:
        index - index at which the value should be set
        Returns:
        value found at the given index
      • toByteArray

        public byte[] toByteArray()
        Get bytes representing the internal data structure with which an IntArrayCompressed can be reconstructed.
        Returns:
        bytes representing the internal data structure with which an IntArrayCompressed can be reconstructed