Interface Hasher
put(int)
, put(long)
, etc) to bytes in
little-endian order.
Warning: The result of calling any methods after calling hash()
is undefined.
Warning: Using a specific character encoding when hashing a CharSequence
with
put(CharSequence, Charset)
is generally only useful for cross-language
compatibility (otherwise prefer #putUnencodedChars
). However, the character encodings
must be identical across languages. Also beware that Charset
definitions may occasionally
change between Java releases.
Warning: Chunks of data that are put into the Hasher
are not delimited. The
resulting HashCode
is dependent only on the bytes inserted, and the order in which they
were inserted, not how those bytes were chunked into discrete put() operations. For example, the
following three expressions all generate colliding hash codes:
newHasher().putByte(b1).putByte(b2).putByte(b3).hash()
newHasher().putByte(b1).putBytes(new byte[] { b2, b3 }).hash()
newHasher().putBytes(new byte[] { b1, b2, b3 }).hash()
If you wish to avoid this, you should either prepend or append the size of each chunk. Keep in
mind that when dealing with char sequences, the encoded form of two concatenated char sequences
is not equivalent to the concatenation of their encoded form. Therefore,
put(CharSequence, Charset)
should only be used consistently with complete
sequences and not broken into chunks.
- Since:
- 11.0
- Author:
- Kevin Bourrillion
-
Method Summary
Modifier and TypeMethodDescriptioncom.google.common.hash.HashCode
hash()
Computes a hash code based on the data that have been provided to this hasher.put
(boolean b) Equivalent toputByte(b ? (byte) 1 : (byte) 0)
.put
(byte b) put
(byte[] bytes) put
(byte[] bytes, int off, int len) put
(char c) put
(char[] chars) put
(char[] chars, int off, int len) put
(double d) Equivalent toputLong(Double.doubleToRawLongBits(d))
.put
(float f) Equivalent toputInt(Float.floatToRawIntBits(f))
.put
(int i) put
(long l) put
(short s) put
(CharSequence charSequence) Equivalent to processing eachchar
value in theCharSequence
, in order.put
(CharSequence charSequence, Charset charset) Equivalent toputBytes(charSequence.toString().getBytes(charset))
.put
(ByteBuffer bytes) <T> Hasher
put
(T instance, com.google.common.hash.Funnel<? super T> funnel) A simple convenience forfunnel.funnel(object, this)
.
-
Method Details
-
put
- Parameters:
b
-- Returns:
-
put
- Parameters:
bytes
-- Returns:
-
put
- Parameters:
bytes
-off
-len
-- Returns:
-
put
- Parameters:
bytes
-- Returns:
-
put
- Parameters:
s
-- Returns:
-
put
- Parameters:
i
-- Returns:
-
put
- Parameters:
l
-- Returns:
-
put
Equivalent toputInt(Float.floatToRawIntBits(f))
.- Parameters:
f
-- Returns:
-
put
Equivalent toputLong(Double.doubleToRawLongBits(d))
.- Parameters:
d
-- Returns:
-
put
Equivalent toputByte(b ? (byte) 1 : (byte) 0)
.- Parameters:
b
-- Returns:
-
put
- Parameters:
c
-- Returns:
-
put
- Parameters:
chars
-- Returns:
-
put
- Parameters:
chars
-off
-len
-- Returns:
-
put
Equivalent to processing eachchar
value in theCharSequence
, in order. In other words, no character encoding is performed; the low byte and high byte of eachchar
are hashed directly (in that order). The input must not be updated while this method is in progress.Warning: This method will produce different output than most other languages do when running the same hash function on the equivalent input. For cross-language compatibility, use
#putString
, usually with a charset of UTF-8. For other use cases, useputUnencodedChars
.- Parameters:
charSequence
-- Returns:
- Since:
- 15.0 (since 11.0 as putString(CharSequence)).
-
put
Equivalent toputBytes(charSequence.toString().getBytes(charset))
.Warning: This method, which reencodes the input before hashing it, is useful only for cross-language compatibility. For other use cases, prefer
#putUnencodedChars
, which is faster, produces the same output across Java releases, and hashes everychar
in the input, even if some are invalid.- Parameters:
charSequence
-charset
-- Returns:
-
put
A simple convenience forfunnel.funnel(object, this)
.- Type Parameters:
T
-- Parameters:
instance
-funnel
-- Returns:
-
hash
com.google.common.hash.HashCode hash()Computes a hash code based on the data that have been provided to this hasher. The result is unspecified if this method is called more than once on the same instance.- Returns:
-