Class DataInput

    • Constructor Summary

      Constructors 
      Constructor Description
      DataInput()  
    • Method Summary

      All Methods Instance Methods Abstract Methods Concrete Methods 
      Modifier and Type Method Description
      DataInput clone()
      Returns a clone of this stream.
      abstract byte readByte()
      Reads and returns a single byte.
      abstract void readBytes​(byte[] b, int offset, int len)
      Reads a specified number of bytes into an array at the specified offset.
      void readBytes​(byte[] b, int offset, int len, boolean useBuffer)
      Reads a specified number of bytes into an array at the specified offset with control over whether the read should be buffered (callers who have their own buffer should pass in "false" for useBuffer).
      void readFloats​(float[] floats, int offset, int len)
      Reads a specified number of floats into an array at the specified offset.
      protected void readGroupVInt​(long[] dst, int offset)
      Override if you have a efficient implementation.
      void readGroupVInts​(long[] dst, int limit)
      Read all the group varints, including the tail vints.
      int readInt()
      Reads four bytes and returns an int (LE byte order).
      void readInts​(int[] dst, int offset, int length)
      Reads a specified number of ints into an array at the specified offset.
      long readLong()
      Reads eight bytes and returns a long (LE byte order).
      void readLongs​(long[] dst, int offset, int length)
      Read a specified number of longs.
      java.util.Map<java.lang.String,​java.lang.String> readMapOfStrings()
      Reads a Map<String,String> previously written with DataOutput.writeMapOfStrings(Map).
      java.util.Set<java.lang.String> readSetOfStrings()
      Reads a Set<String> previously written with DataOutput.writeSetOfStrings(Set).
      short readShort()
      Reads two bytes and returns a short (LE byte order).
      java.lang.String readString()
      Reads a string.
      int readVInt()
      Reads an int stored in variable-length format.
      long readVLong()
      Reads a long stored in variable-length format.
      private long readVLong​(boolean allowNegative)  
      int readZInt()
      Read a zig-zag-encoded variable-length integer.
      long readZLong()
      Read a zig-zag-encoded variable-length integer.
      abstract void skipBytes​(long numBytes)
      Skip over numBytes bytes.
      • Methods inherited from class java.lang.Object

        equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
    • Constructor Detail

      • DataInput

        public DataInput()
    • Method Detail

      • readByte

        public abstract byte readByte()
                               throws java.io.IOException
        Reads and returns a single byte.
        Throws:
        java.io.IOException
        See Also:
        DataOutput.writeByte(byte)
      • readBytes

        public abstract void readBytes​(byte[] b,
                                       int offset,
                                       int len)
                                throws java.io.IOException
        Reads a specified number of bytes into an array at the specified offset.
        Parameters:
        b - the array to read bytes into
        offset - the offset in the array to start storing bytes
        len - the number of bytes to read
        Throws:
        java.io.IOException
        See Also:
        DataOutput.writeBytes(byte[],int)
      • readBytes

        public void readBytes​(byte[] b,
                              int offset,
                              int len,
                              boolean useBuffer)
                       throws java.io.IOException
        Reads a specified number of bytes into an array at the specified offset with control over whether the read should be buffered (callers who have their own buffer should pass in "false" for useBuffer). Currently only BufferedIndexInput respects this parameter.
        Parameters:
        b - the array to read bytes into
        offset - the offset in the array to start storing bytes
        len - the number of bytes to read
        useBuffer - set to false if the caller will handle buffering.
        Throws:
        java.io.IOException
        See Also:
        DataOutput.writeBytes(byte[],int)
      • readGroupVInts

        public final void readGroupVInts​(long[] dst,
                                         int limit)
                                  throws java.io.IOException
        Read all the group varints, including the tail vints. we need a long[] because this is what postings are using, all longs are actually required to be integers.
        Parameters:
        dst - the array to read ints into.
        limit - the number of int values to read.
        Throws:
        java.io.IOException
      • readGroupVInt

        protected void readGroupVInt​(long[] dst,
                                     int offset)
                              throws java.io.IOException
        Override if you have a efficient implementation. In general this is when the input supports random access.
        Throws:
        java.io.IOException
      • readVInt

        public int readVInt()
                     throws java.io.IOException
        Reads an int stored in variable-length format. Reads between one and five bytes. Smaller values take fewer bytes. Negative numbers are supported, but should be avoided.

        The format is described further in DataOutput.writeVInt(int).

        Throws:
        java.io.IOException
        See Also:
        DataOutput.writeVInt(int)
      • readLongs

        public void readLongs​(long[] dst,
                              int offset,
                              int length)
                       throws java.io.IOException
        Read a specified number of longs.
        Throws:
        java.io.IOException
      • readInts

        public void readInts​(int[] dst,
                             int offset,
                             int length)
                      throws java.io.IOException
        Reads a specified number of ints into an array at the specified offset.
        Parameters:
        dst - the array to read bytes into
        offset - the offset in the array to start storing ints
        length - the number of ints to read
        Throws:
        java.io.IOException
      • readFloats

        public void readFloats​(float[] floats,
                               int offset,
                               int len)
                        throws java.io.IOException
        Reads a specified number of floats into an array at the specified offset.
        Parameters:
        floats - the array to read bytes into
        offset - the offset in the array to start storing floats
        len - the number of floats to read
        Throws:
        java.io.IOException
      • readVLong

        public long readVLong()
                       throws java.io.IOException
        Reads a long stored in variable-length format. Reads between one and nine bytes. Smaller values take fewer bytes. Negative numbers are not supported.

        The format is described further in DataOutput.writeVInt(int).

        Throws:
        java.io.IOException
        See Also:
        DataOutput.writeVLong(long)
      • readVLong

        private long readVLong​(boolean allowNegative)
                        throws java.io.IOException
        Throws:
        java.io.IOException
      • readString

        public java.lang.String readString()
                                    throws java.io.IOException
        Reads a string.
        Throws:
        java.io.IOException
        See Also:
        DataOutput.writeString(String)
      • clone

        public DataInput clone()
        Returns a clone of this stream.

        Clones of a stream access the same data, and are positioned at the same point as the stream they were cloned from.

        Expert: Subclasses must ensure that clones may be positioned at different points in the input from each other and from the stream they were cloned from.

        Overrides:
        clone in class java.lang.Object
      • readMapOfStrings

        public java.util.Map<java.lang.String,​java.lang.String> readMapOfStrings()
                                                                                throws java.io.IOException
        Reads a Map<String,String> previously written with DataOutput.writeMapOfStrings(Map).
        Returns:
        An immutable map containing the written contents.
        Throws:
        java.io.IOException
      • readSetOfStrings

        public java.util.Set<java.lang.String> readSetOfStrings()
                                                         throws java.io.IOException
        Reads a Set<String> previously written with DataOutput.writeSetOfStrings(Set).
        Returns:
        An immutable set containing the written contents.
        Throws:
        java.io.IOException
      • skipBytes

        public abstract void skipBytes​(long numBytes)
                                throws java.io.IOException
        Skip over numBytes bytes. This method may skip bytes in whatever way is most optimal, and may not have the same behavior as reading the skipped bytes. In general, negative numBytes are not supported.
        Throws:
        java.io.IOException