WrappedRecordReader (Apache Hadoop Main 2.10.2 API)

java.lang.Object
- org.apache.hadoop.mapred.join.WrappedRecordReader<K,U>

All Implemented Interfaces:

Comparable<ComposableRecordReader<K,?>>, Configurable, ComposableRecordReader<K,U>, RecordReader<K,U>
```
@InterfaceAudience.Public
@InterfaceStability.Stable
public class WrappedRecordReader<K extends WritableComparable,U extends Writable>
extends Object
implements ComposableRecordReader<K,U>, Configurable
```
Proxy class for a RecordReader participating in the join framework. This class keeps track of the "head" key-value pair for the provided RecordReader and keeps a store of values matching a key when this source is participating in a join.

Method Summary

Methods
Modifier and Type	Method and Description
`void`	`accept(org.apache.hadoop.mapred.join.CompositeRecordReader.JoinCollector i, K key)` Add an iterator to the collector at the position occupied by this RecordReader over the values in this stream paired with the key provided (ie register a stream of values from this source matching K with a collector).
`void`	`close()` Forward close request to proxied RR.
`int`	`compareTo(ComposableRecordReader<K,?> other)` Implement Comparable contract (compare key at head of proxied RR with that of another).
`K`	`createKey()` Request new key from proxied RR.
`U`	`createValue()` Request new value from proxied RR.
`boolean`	`equals(Object other)` Return true iff compareTo(other) retn true.
`Configuration`	`getConf()` Return the configuration used by this object.
`long`	`getPos()` Request position from proxied RR.
`float`	`getProgress()` Request progress from proxied RR.
`int`	`hashCode()`
`boolean`	`hasNext()` Return true if the RR- including the k,v pair stored in this object- is exhausted.
`int`	`id()` Return the position in the collector this class occupies.
`K`	`key()` Return the key at the head of this RR.
`void`	`key(K qkey)` Clone the key at the head of this RR into the object supplied.
`protected boolean`	`next()` Read the next k,v pair into the head of this object; return true iff the RR and this are exhausted.
`boolean`	`next(K key, U value)` Write key-value pair at the head of this stream to the objects provided; get next key-value pair from proxied RR.
`void`	`setConf(Configuration conf)` Set the configuration to be used by this object.
`void`	`skip(K key)` Skip key-value pairs with keys less than or equal to the key provided.

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

- Method Detail
  - id
```
public int id()
```
    Return the position in the collector this class occupies.
    
    Specified by:
    
    id in interface ComposableRecordReader<K extends WritableComparable,U extends Writable>
  - key
```
public K key()
```
    Return the key at the head of this RR.
    
    Specified by:
    
    key in interface ComposableRecordReader<K extends WritableComparable,U extends Writable>
  - key
```
public void key(K qkey)
         throws IOException
```
    Clone the key at the head of this RR into the object supplied.
    
    Specified by:
    
    key in interface ComposableRecordReader<K extends WritableComparable,U extends Writable>
    
    Throws:
    
    IOException
  - hasNext
```
public boolean hasNext()
```
    Return true if the RR- including the k,v pair stored in this object- is exhausted.
    
    Specified by:
    
    hasNext in interface ComposableRecordReader<K extends WritableComparable,U extends Writable>
  - skip
```
public void skip(K key)
          throws IOException
```
    Skip key-value pairs with keys less than or equal to the key provided.
    
    Specified by:
    
    skip in interface ComposableRecordReader<K extends WritableComparable,U extends Writable>
    
    Throws:
    
    IOException
  - next
```
protected boolean next()
                throws IOException
```
    Read the next k,v pair into the head of this object; return true iff the RR and this are exhausted.
    
    Throws:
    
    IOException
  - accept
```
public void accept(org.apache.hadoop.mapred.join.CompositeRecordReader.JoinCollector i,
          K key)
            throws IOException
```
    Add an iterator to the collector at the position occupied by this RecordReader over the values in this stream paired with the key provided (ie register a stream of values from this source matching K with a collector).
    
    Specified by:
    
    accept in interface ComposableRecordReader<K extends WritableComparable,U extends Writable>
    
    Throws:
    
    IOException
  - next
```
public boolean next(K key,
           U value)
             throws IOException
```
    Write key-value pair at the head of this stream to the objects provided; get next key-value pair from proxied RR.
    
    Specified by:
    
    next in interface RecordReader<K extends WritableComparable,U extends Writable>
    
    Parameters:
    key - the key to read data into
    value - the value to read data into
    
    Returns:
    true iff a key/value was read, false if at EOF
    
    Throws:
    
    IOException
  - createKey
```
public K createKey()
```
    Request new key from proxied RR.
    
    Specified by:
    
    createKey in interface RecordReader<K extends WritableComparable,U extends Writable>
    
    Returns:
    a new key object.
  - createValue
```
public U createValue()
```
    Request new value from proxied RR.
    
    Specified by:
    
    createValue in interface RecordReader<K extends WritableComparable,U extends Writable>
    
    Returns:
    a new value object.
  - getProgress
```
public float getProgress()
                  throws IOException
```
    Request progress from proxied RR.
    
    Specified by:
    
    getProgress in interface RecordReader<K extends WritableComparable,U extends Writable>
    
    Returns:
    progress from 0.0 to 1.0.
    
    Throws:
    
    IOException
  - getPos
```
public long getPos()
            throws IOException
```
    Request position from proxied RR.
    
    Specified by:
    
    getPos in interface RecordReader<K extends WritableComparable,U extends Writable>
    
    Returns:
    the current position in the input.
    
    Throws:
    
    IOException
  - close
```
public void close()
           throws IOException
```
    Forward close request to proxied RR.
    
    Specified by:
    
    close in interface RecordReader<K extends WritableComparable,U extends Writable>
    
    Throws:
    
    IOException
  - compareTo
```
public int compareTo(ComposableRecordReader<K,?> other)
```
    Implement Comparable contract (compare key at head of proxied RR with that of another).
    
    Specified by:
    
    compareTo in interface Comparable<ComposableRecordReader<K extends WritableComparable,?>>
  - equals
```
public boolean equals(Object other)
```
    Return true iff compareTo(other) retn true.
    
    Overrides:
    
    equals in class Object
  - hashCode
```
public int hashCode()
```
    Overrides:
    
    hashCode in class Object
  - setConf
```
public void setConf(Configuration conf)
```
    Description copied from interface: Configurable
    
    Set the configuration to be used by this object.
    
    Specified by:
    
    setConf in interface Configurable
  - getConf
```
public Configuration getConf()
```
    Description copied from interface: Configurable
    
    Return the configuration used by this object.
    
    Specified by:
    
    getConf in interface Configurable

Class WrappedRecordReader<K extends WritableComparable,U extends Writable>

Method Summary

Methods inherited from class java.lang.Object

Method Detail

id

key

key

hasNext

skip

next

accept

next

createKey

createValue

getProgress

getPos

close

compareTo

equals

hashCode

setConf

getConf