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java.lang.Object org.apache.hadoop.io.ObjectWritable
@InterfaceAudience.Public @InterfaceStability.Stable public class ObjectWritable
A polymorphic Writable that writes an instance with it's class name. Handles arrays, strings and primitive types without a Writable wrapper.
Constructor Summary | |
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ObjectWritable()
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ObjectWritable(Class declaredClass,
Object instance)
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ObjectWritable(Object instance)
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Method Summary | |
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Object |
get()
Return the instance, or null if none. |
Configuration |
getConf()
Return the configuration used by this object. |
Class |
getDeclaredClass()
Return the class this is meant to be. |
static Class<?> |
loadClass(Configuration conf,
String className)
Find and load the class with given name className by first finding it in the specified conf. |
void |
readFields(DataInput in)
Deserialize the fields of this object from in . |
static Object |
readObject(DataInput in,
Configuration conf)
Read a Writable , String , primitive type, or an array of
the preceding. |
static Object |
readObject(DataInput in,
ObjectWritable objectWritable,
Configuration conf)
Read a Writable , String , primitive type, or an array of
the preceding. |
void |
set(Object instance)
Reset the instance. |
void |
setConf(Configuration conf)
Set the configuration to be used by this object. |
String |
toString()
|
void |
write(DataOutput out)
Serialize the fields of this object to out . |
static void |
writeObject(DataOutput out,
Object instance,
Class declaredClass,
Configuration conf)
Write a Writable , String , primitive type, or an array of
the preceding. |
static void |
writeObject(DataOutput out,
Object instance,
Class declaredClass,
Configuration conf,
boolean allowCompactArrays)
Write a Writable , String , primitive type, or an array of
the preceding. |
Methods inherited from class java.lang.Object |
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait |
Constructor Detail |
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public ObjectWritable()
public ObjectWritable(Object instance)
public ObjectWritable(Class declaredClass, Object instance)
Method Detail |
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public Object get()
public Class getDeclaredClass()
public void set(Object instance)
public String toString()
toString
in class Object
public void readFields(DataInput in) throws IOException
Writable
in
.
For efficiency, implementations should attempt to re-use storage in the existing object where possible.
readFields
in interface Writable
in
- DataInput
to deseriablize this object from.
IOException
public void write(DataOutput out) throws IOException
Writable
out
.
write
in interface Writable
out
- DataOuput
to serialize this object into.
IOException
public static void writeObject(DataOutput out, Object instance, Class declaredClass, Configuration conf) throws IOException
Writable
, String
, primitive type, or an array of
the preceding.
IOException
public static void writeObject(DataOutput out, Object instance, Class declaredClass, Configuration conf, boolean allowCompactArrays) throws IOException
Writable
, String
, primitive type, or an array of
the preceding.
allowCompactArrays
- - set true for RPC and internal or intra-cluster
usages. Set false for inter-cluster, File, and other persisted output
usages, to preserve the ability to interchange files with other clusters
that may not be running the same version of software. Sometime in ~2013
we can consider removing this parameter and always using the compact format.
IOException
public static Object readObject(DataInput in, Configuration conf) throws IOException
Writable
, String
, primitive type, or an array of
the preceding.
IOException
public static Object readObject(DataInput in, ObjectWritable objectWritable, Configuration conf) throws IOException
Writable
, String
, primitive type, or an array of
the preceding.
IOException
public static Class<?> loadClass(Configuration conf, String className)
public void setConf(Configuration conf)
Configurable
setConf
in interface Configurable
public Configuration getConf()
Configurable
getConf
in interface Configurable
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