Hash (I2P Anonymous Network - Java Documentation

java.lang.Object
- net.i2p.data.DataStructureImpl
- - net.i2p.data.SimpleDataStructure
  - - net.i2p.data.Hash

All Implemented Interfaces:

Serializable, DataStructure

Direct Known Subclasses:

LocalHash, Peer
```
public class Hash
extends SimpleDataStructure
```
Defines the hash as defined by the I2P data structure spec. A hash is the SHA-256 of some data, taking up 32 bytes.

Author:

jrandom

See Also:

Serialized Form

Field Summary

Fields
Modifier and Type Field Description

static Hash FAKE_HASH

static int HASH_LENGTH
- Fields inherited from class net.i2p.data.SimpleDataStructure
  _data

Fields
Modifier and Type	Field	Description
`static Hash`	`FAKE_HASH`
`static int`	`HASH_LENGTH`

Constructor Summary

Constructors
Constructor Description

Hash()

Hash(byte[] data)

Constructors
Constructor	Description
`Hash()`
`Hash(byte[] data)`

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`static void`	`clearCache()`
`static Hash`	`create(byte[] data)`	Pull from cache or return new WARNING - If the SDS is found in the cache, the passed-in byte array will be returned to the SimpleByteCache for reuse.
`static Hash`	`create(byte[] data, int off)`	Pull from cache or return new
`static Hash`	`create(InputStream in)`	Pull from cache or return new
`int`	`hashCode()`	a Hash is a hash, so just use the first 4 bytes for speed
`int`	`length()`	The legal length of the byte array in this data structure
`void`	`readBytes(InputStream in)`	Sets the data.
`void`	`setData(byte[] data)`	Sets the data.
`String`	`toBase32()`	For convenience.
`String`	`toBase64()`	render the structure into modified base 64 notation

Methods inherited from class net.i2p.data.DataStructureImpl
read

Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from class net.i2p.data.SimpleDataStructure
calculateHash, equals, fromBase64, fromByteArray, getData, toByteArray, toString, writeBytes

- Field Detail
  - HASH_LENGTH
```
public static final int HASH_LENGTH
```
    See Also:
    
    Constant Field Values
  - FAKE_HASH
```
public static final Hash FAKE_HASH
```
- Constructor Detail
  - Hash
```
public Hash()
```
  - Hash
```
public Hash(byte[] data)
```
    Throws:
    
    IllegalArgumentException - if data is not 32 bytes (null is ok)
- Method Detail
  - create
```
public static Hash create(byte[] data)
```
    Pull from cache or return new WARNING - If the SDS is found in the cache, the passed-in byte array will be returned to the SimpleByteCache for reuse. Do NOT save a reference to the passed-in data, or use or modify it, after this call. Ignore this warning and you WILL corrupt the cache or other data structures.
    
    Throws:
    
    IllegalArgumentException - if data is not the correct number of bytes
    
    Since:
    
    0.8.3
  - create
```
public static Hash create(byte[] data,
                          int off)
```
    Pull from cache or return new
    
    Throws:
    
    ArrayIndexOutOfBoundsException - if not enough bytes
    
    Since:
    
    0.8.3
  - create
```
public static Hash create(InputStream in)
                   throws IOException
```
    Pull from cache or return new
    
    Throws:
    
    IOException
    
    Since:
    
    0.8.3
  - length
```
public int length()
```
    Description copied from class: SimpleDataStructure
    
    The legal length of the byte array in this data structure
    
    Specified by:
    
    length in class SimpleDataStructure
  - setData
```
public void setData(byte[] data)
```
    Description copied from class: SimpleDataStructure
    
    Sets the data.
    
    Overrides:
    
    setData in class SimpleDataStructure
    
    Parameters:
    
    data - of correct length, or null
    
    Throws:
    
    IllegalArgumentException - if data is not 32 bytes (null is ok)
  - readBytes
```
public void readBytes(InputStream in)
               throws DataFormatException,
                      IOException
```
    Description copied from class: SimpleDataStructure
    
    Sets the data.
    
    Specified by:
    
    readBytes in interface DataStructure
    
    Overrides:
    
    readBytes in class SimpleDataStructure
    
    Parameters:
    
    in - the stream to read
    
    Throws:
    
    DataFormatException - if the data is improperly formatted
    
    IOException - if there was a problem reading the stream
  - hashCode
```
public int hashCode()
```
    a Hash is a hash, so just use the first 4 bytes for speed
    
    Overrides:
    
    hashCode in class SimpleDataStructure
  - toBase64
```
public String toBase64()
```
    Description copied from interface: DataStructure
    
    render the structure into modified base 64 notation
    
    Specified by:
    
    toBase64 in interface DataStructure
    
    Overrides:
    
    toBase64 in class SimpleDataStructure
    
    Returns:
    
    null on error
  - toBase32
```
public String toBase32()
```
    For convenience.
    
    Returns:
    
    "{52 chars}.b32.i2p" or null if data not set.
    
    Since:
    
    0.9.25
  - clearCache
```
public static void clearCache()
```
    Since:
    
    0.9.17

Class Hash

Field Summary

Fields inherited from class net.i2p.data.SimpleDataStructure

Constructor Summary

Method Summary

Methods inherited from class net.i2p.data.DataStructureImpl

Methods inherited from class java.lang.Object

Methods inherited from class net.i2p.data.SimpleDataStructure

Field Detail

HASH_LENGTH

FAKE_HASH

Constructor Detail

Hash

Hash

Method Detail

create

create

create

length

setData

readBytes

hashCode

toBase64

toBase32

clearCache