WritableUtils (Apache Hadoop Main 2.7.4 API)

java.lang.Object
- org.apache.hadoop.io.WritableUtils

@InterfaceAudience.Public
 @InterfaceStability.Stable
public final class WritableUtils
extends Object

Constructor Summary

Constructors
Constructor and Description

WritableUtils()

Constructors
Constructor and Description
`WritableUtils()`

Method Summary

All Methods Static Methods Concrete Methods Deprecated Methods
Modifier and Type	Method and Description
`static <T extends Writable> T`	`clone(T orig, Configuration conf)` Make a copy of a writable object using serialization to a buffer.
`static void`	`cloneInto(Writable dst, Writable src)` Deprecated. use ReflectionUtils.cloneInto instead.
`static int`	`decodeVIntSize(byte value)` Parse the first byte of a vint/vlong to determine the number of bytes
`static void`	`displayByteArray(byte[] record)`
`static int`	`getVIntSize(long i)` Get the encoded length if an integer is stored in a variable-length format
`static boolean`	`isNegativeVInt(byte value)` Given the first byte of a vint/vlong, determine the sign
`static byte[]`	`readCompressedByteArray(DataInput in)`
`static String`	`readCompressedString(DataInput in)`
`static String[]`	`readCompressedStringArray(DataInput in)`
`static <T extends Enum<T>> T`	`readEnum(DataInput in, Class<T> enumType)` Read an Enum value from DataInput, Enums are read and written using String values.
`static String`	`readString(DataInput in)`
`static String[]`	`readStringArray(DataInput in)`
`static String`	`readStringSafely(DataInput in, int maxLength)` Read a string, but check it for sanity.
`static int`	`readVInt(DataInput stream)` Reads a zero-compressed encoded integer from input stream and returns it.
`static int`	`readVIntInRange(DataInput stream, int lower, int upper)` Reads an integer from the input stream and returns it.
`static long`	`readVLong(DataInput stream)` Reads a zero-compressed encoded long from input stream and returns it.
`static void`	`skipCompressedByteArray(DataInput in)`
`static void`	`skipFully(DataInput in, int len)` Skip len number of bytes in input streamin
`static byte[]`	`toByteArray(Writable... writables)` Convert writables to a byte array
`static int`	`writeCompressedByteArray(DataOutput out, byte[] bytes)`
`static int`	`writeCompressedString(DataOutput out, String s)`
`static void`	`writeCompressedStringArray(DataOutput out, String[] s)`
`static void`	`writeEnum(DataOutput out, Enum<?> enumVal)` writes String value of enum to DataOutput.
`static void`	`writeString(DataOutput out, String s)`
`static void`	`writeStringArray(DataOutput out, String[] s)`
`static void`	`writeVInt(DataOutput stream, int i)` Serializes an integer to a binary stream with zero-compressed encoding.
`static void`	`writeVLong(DataOutput stream, long i)` Serializes a long to a binary stream with zero-compressed encoding.

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

- Constructor Detail
  - WritableUtils
```
public WritableUtils()
```
- Method Detail
  - readCompressedByteArray
```
public static byte[] readCompressedByteArray(DataInput in)
                                      throws IOException
```
    Throws:
    
    IOException
  - skipCompressedByteArray
```
public static void skipCompressedByteArray(DataInput in)
                                    throws IOException
```
    Throws:
    
    IOException
  - writeCompressedByteArray
```
public static int writeCompressedByteArray(DataOutput out,
                                           byte[] bytes)
                                    throws IOException
```
    Throws:
    
    IOException
  - readCompressedString
```
public static String readCompressedString(DataInput in)
                                   throws IOException
```
    Throws:
    
    IOException
  - writeCompressedString
```
public static int writeCompressedString(DataOutput out,
                                        String s)
                                 throws IOException
```
    Throws:
    
    IOException
  - writeString
```
public static void writeString(DataOutput out,
                               String s)
                        throws IOException
```
    Throws:
    
    IOException
  - readString
```
public static String readString(DataInput in)
                         throws IOException
```
    Throws:
    
    IOException
  - writeStringArray
```
public static void writeStringArray(DataOutput out,
                                    String[] s)
                             throws IOException
```
    Throws:
    
    IOException
  - writeCompressedStringArray
```
public static void writeCompressedStringArray(DataOutput out,
                                              String[] s)
                                       throws IOException
```
    Throws:
    
    IOException
  - readStringArray
```
public static String[] readStringArray(DataInput in)
                                throws IOException
```
    Throws:
    
    IOException
  - readCompressedStringArray
```
public static String[] readCompressedStringArray(DataInput in)
                                          throws IOException
```
    Throws:
    
    IOException
  - displayByteArray
```
public static void displayByteArray(byte[] record)
```
  - clone
```
public static <T extends Writable> T clone(T orig,
                                           Configuration conf)
```
    Make a copy of a writable object using serialization to a buffer.
    
    Parameters:
    
    orig - The object to copy
    
    Returns:
    
    The copied object
  - cloneInto
```
@Deprecated
public static void cloneInto(Writable dst,
                                         Writable src)
                                  throws IOException
```
    Deprecated. use ReflectionUtils.cloneInto instead.
    
    Make a copy of the writable object using serialiation to a buffer
    
    Parameters:
    
    dst - the object to copy from
    
    src - the object to copy into, which is destroyed
    
    Throws:
    
    IOException
  - writeVInt
```
public static void writeVInt(DataOutput stream,
                             int i)
                      throws IOException
```
    Serializes an integer to a binary stream with zero-compressed encoding. For -112 <= i <= 127, only one byte is used with the actual value. For other values of i, the first byte value indicates whether the integer is positive or negative, and the number of bytes that follow. If the first byte value v is between -113 and -116, the following integer is positive, with number of bytes that follow are -(v+112). If the first byte value v is between -121 and -124, the following integer is negative, with number of bytes that follow are -(v+120). Bytes are stored in the high-non-zero-byte-first order.
    
    Parameters:
    
    stream - Binary output stream
    
    i - Integer to be serialized
    
    Throws:
    
    IOException
  - writeVLong
```
public static void writeVLong(DataOutput stream,
                              long i)
                       throws IOException
```
    Serializes a long to a binary stream with zero-compressed encoding. For -112 <= i <= 127, only one byte is used with the actual value. For other values of i, the first byte value indicates whether the long is positive or negative, and the number of bytes that follow. If the first byte value v is between -113 and -120, the following long is positive, with number of bytes that follow are -(v+112). If the first byte value v is between -121 and -128, the following long is negative, with number of bytes that follow are -(v+120). Bytes are stored in the high-non-zero-byte-first order.
    
    Parameters:
    
    stream - Binary output stream
    
    i - Long to be serialized
    
    Throws:
    
    IOException
  - readVLong
```
public static long readVLong(DataInput stream)
                      throws IOException
```
    Reads a zero-compressed encoded long from input stream and returns it.
    
    Parameters:
    
    stream - Binary input stream
    
    Returns:
    
    deserialized long from stream.
    
    Throws:
    
    IOException
  - readVInt
```
public static int readVInt(DataInput stream)
                    throws IOException
```
    Reads a zero-compressed encoded integer from input stream and returns it.
    
    Parameters:
    
    stream - Binary input stream
    
    Returns:
    
    deserialized integer from stream.
    
    Throws:
    
    IOException
  - readVIntInRange
```
public static int readVIntInRange(DataInput stream,
                                  int lower,
                                  int upper)
                           throws IOException
```
    Reads an integer from the input stream and returns it. This function validates that the integer is between [lower, upper], inclusive.
    
    Parameters:
    
    stream - Binary input stream
    
    Returns:
    
    deserialized integer from stream
    
    Throws:
    
    IOException
  - isNegativeVInt
```
public static boolean isNegativeVInt(byte value)
```
    Given the first byte of a vint/vlong, determine the sign
    
    Parameters:
    
    value - the first byte
    
    Returns:
    
    is the value negative
  - decodeVIntSize
```
public static int decodeVIntSize(byte value)
```
    Parse the first byte of a vint/vlong to determine the number of bytes
    
    Parameters:
    
    value - the first byte of the vint/vlong
    
    Returns:
    
    the total number of bytes (1 to 9)
  - getVIntSize
```
public static int getVIntSize(long i)
```
    Get the encoded length if an integer is stored in a variable-length format
    
    Returns:
    
    the encoded length
  - readEnum
```
public static <T extends Enum<T>> T readEnum(DataInput in,
                                             Class<T> enumType)
                                      throws IOException
```
    Read an Enum value from DataInput, Enums are read and written using String values.
    
    Type Parameters:
    
    T - Enum type
    
    Parameters:
    
    in - DataInput to read from
    
    enumType - Class type of Enum
    
    Returns:
    
    Enum represented by String read from DataInput
    
    Throws:
    
    IOException
  - writeEnum
```
public static void writeEnum(DataOutput out,
                             Enum<?> enumVal)
                      throws IOException
```
    writes String value of enum to DataOutput.
    
    Parameters:
    
    out - Dataoutput stream
    
    enumVal - enum value
    
    Throws:
    
    IOException
  - skipFully
```
public static void skipFully(DataInput in,
                             int len)
                      throws IOException
```
    Skip len number of bytes in input streamin
    
    Parameters:
    
    in - input stream
    
    len - number of bytes to skip
    
    Throws:
    
    IOException - when skipped less number of bytes
  - toByteArray
```
public static byte[] toByteArray(Writable... writables)
```
    Convert writables to a byte array
  - readStringSafely
```
public static String readStringSafely(DataInput in,
                                      int maxLength)
                               throws IOException,
                                      IllegalArgumentException
```
    Read a string, but check it for sanity. The format consists of a vint followed by the given number of bytes.
    
    Parameters:
    
    in - the stream to read from
    
    maxLength - the largest acceptable length of the encoded string
    
    Returns:
    
    the bytes as a string
    
    Throws:
    
    IOException - if reading from the DataInput fails
    
    IllegalArgumentException - if the encoded byte size for string is negative or larger than maxSize. Only the vint is read.

Class WritableUtils

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

WritableUtils

Method Detail

readCompressedByteArray

skipCompressedByteArray

writeCompressedByteArray

readCompressedString

writeCompressedString

writeString

readString

writeStringArray

writeCompressedStringArray

readStringArray

readCompressedStringArray

displayByteArray

clone

cloneInto

writeVInt

writeVLong

readVLong

readVInt

readVIntInRange

isNegativeVInt

decodeVIntSize

getVIntSize

readEnum

writeEnum

skipFully

toByteArray

readStringSafely