@Beta public interface Hasher extends PrimitiveSink
A PrimitiveSink that can compute a hash code after reading the input. Each hasher should translate all multibyte values (putInt(int), putLong(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 putString(CharSequence, Charset) is generally only useful for cross-language compatibility (otherwise prefer putUnencodedChars(java.lang.CharSequence)). 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, putString(CharSequence, Charset) should only be used consistently with complete sequences and not broken into chunks.
| Modifier and Type | Method and Description |
|---|---|
HashCode |
hash()
Computes a hash code based on the data that have been provided to this hasher.
|
int |
hashCode()
Deprecated.
This returns
Object.hashCode(); you almost certainly mean to call hash().asInt(). |
Hasher |
putBoolean(boolean b)
Equivalent to
putByte(b ? (byte) 1 : (byte) 0). |
Hasher |
putByte(byte b)
Puts a byte into this sink.
|
Hasher |
putBytes(byte[] bytes)
Puts an array of bytes into this sink.
|
Hasher |
putBytes(byte[] bytes,
int off,
int len)
Puts a chunk of an array of bytes into this sink.
|
Hasher |
putChar(char c)
Puts a character into this sink.
|
Hasher |
putDouble(double d)
Equivalent to
putLong(Double.doubleToRawLongBits(d)). |
Hasher |
putFloat(float f)
Equivalent to
putInt(Float.floatToRawIntBits(f)). |
Hasher |
putInt(int i)
Puts an int into this sink.
|
Hasher |
putLong(long l)
Puts a long into this sink.
|
<T> Hasher |
putObject(T instance,
Funnel<? super T> funnel)
A simple convenience for
funnel.funnel(object, this). |
Hasher |
putShort(short s)
Puts a short into this sink.
|
Hasher |
putString(CharSequence charSequence,
Charset charset)
Equivalent to
putBytes(charSequence.toString().getBytes(charset)). |
Hasher |
putUnencodedChars(CharSequence charSequence)
Equivalent to processing each
char value in the CharSequence, in order. |
Hasher putByte(byte b)
PrimitiveSinkPuts a byte into this sink.
putByte in interface PrimitiveSinkb - a byteHasher putBytes(byte[] bytes)
PrimitiveSinkPuts an array of bytes into this sink.
putBytes in interface PrimitiveSinkbytes - a byte arrayHasher putBytes(byte[] bytes, int off, int len)
PrimitiveSinkPuts a chunk of an array of bytes into this sink. bytes[off] is the first byte written, bytes[off + len - 1] is the last.
putBytes in interface PrimitiveSinkbytes - a byte arrayoff - the start offset in the arraylen - the number of bytes to writeHasher putShort(short s)
PrimitiveSinkPuts a short into this sink.
putShort in interface PrimitiveSinkHasher putInt(int i)
PrimitiveSinkPuts an int into this sink.
putInt in interface PrimitiveSinkHasher putLong(long l)
PrimitiveSinkPuts a long into this sink.
putLong in interface PrimitiveSinkHasher putFloat(float f)
Equivalent to putInt(Float.floatToRawIntBits(f)).
putFloat in interface PrimitiveSinkHasher putDouble(double d)
Equivalent to putLong(Double.doubleToRawLongBits(d)).
putDouble in interface PrimitiveSinkHasher putBoolean(boolean b)
Equivalent to putByte(b ? (byte) 1 : (byte) 0).
putBoolean in interface PrimitiveSinkHasher putChar(char c)
PrimitiveSinkPuts a character into this sink.
putChar in interface PrimitiveSinkHasher putUnencodedChars(CharSequence charSequence)
Equivalent to processing each char value in the CharSequence, in order. The input must not be updated while this method is in progress.
putUnencodedChars in interface PrimitiveSinkHasher putString(CharSequence charSequence, Charset charset)
Equivalent to putBytes(charSequence.toString().getBytes(charset)).
putString in interface PrimitiveSink<T> Hasher putObject(T instance, Funnel<? super T> funnel)
A simple convenience for funnel.funnel(object, this).
@CheckReturnValue 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.
@Deprecated int hashCode()
Object.hashCode(); you almost certainly mean to call hash().asInt().