PairLexicoder (Apache Accumulo Core 2.0.0 API)

java.lang.Object
- org.apache.accumulo.core.client.lexicoder.AbstractEncoder<T>
- - org.apache.accumulo.core.clientImpl.lexicoder.AbstractLexicoder<ComparablePair<A,B>>
  - - org.apache.accumulo.core.client.lexicoder.PairLexicoder<A,B>

All Implemented Interfaces:

Encoder<ComparablePair<A,B>>, Lexicoder<ComparablePair<A,B>>
```
public class PairLexicoder<A extends Comparable<A>,B extends Comparable<B>>
extends AbstractLexicoder<ComparablePair<A,B>>
```
This class is a lexicoder that sorts a ComparablePair. Each item in the pair is encoded with the given lexicoder and concatenated together. This makes it easy to construct a sortable key based on two components. There are many examples of this- but a key/value relationship is a great one. If we decided we wanted a two-component key where the first component is a string and the second component a date which is reverse sorted, we can do so with the following example:
```
 
 StringLexicoder strEncoder = new StringLexicoder();
 ReverseLexicoder<Date> dateEnc = new ReverseLexicoder<>(new DateLexicoder());
 PairLexicoder<String,Date> pair = new PairLexicoder<>(strEncoder, dateEnc);
 long now = System.currentTimeMillis();
 byte[] pair1 = pair.encode(new ComparablePair<>("com", new Date(now)));
 byte[] pair2 = pair.encode(new ComparablePair<>("com", new Date(now + 500)));
 byte[] pair3 = pair.encode(new ComparablePair<>("org", new Date(now + 1000)));
 
 
```
In the example, pair2 will be sorted before pair1. pair3 will occur last since 'org' is sorted after 'com'. If we just used a DateLexicoder instead of a ReverseLexicoder, pair1 would have been sorted before pair2.
Since:

1.6.0

Constructor Summary

Constructors
Constructor Description

PairLexicoder(Lexicoder<A> firstLexicoder, Lexicoder<B> secondLexicoder)

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`ComparablePair<A,B>`	`decode(byte[] b)`
`protected ComparablePair<A,B>`	`decodeUnchecked(byte[] data, int offset, int len)`	Decodes a byte array without checking if the offset and len exceed the bounds of the actual array.
`byte[]`	`encode(ComparablePair<A,B> data)`

Methods inherited from class org.apache.accumulo.core.client.lexicoder.AbstractEncoder
decode

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

- Constructor Detail
  - PairLexicoder
```
public PairLexicoder(Lexicoder<A> firstLexicoder,
                     Lexicoder<B> secondLexicoder)
```
- Method Detail
  - encode
```
public byte[] encode(ComparablePair<A,B> data)
```
  - decode
```
public ComparablePair<A,B> decode(byte[] b)
```
    Specified by:
    
    decode in interface Encoder<A extends Comparable<A>>
    
    Overrides:
    
    decode in class AbstractEncoder<ComparablePair<A extends Comparable<A>,B extends Comparable<B>>>
  - decodeUnchecked
```
protected ComparablePair<A,B> decodeUnchecked(byte[] data,
                                                    int offset,
                                                    int len)
```
    Description copied from class: AbstractEncoder
    
    Decodes a byte array without checking if the offset and len exceed the bounds of the actual array.
    
    Specified by:
    
    decodeUnchecked in class AbstractEncoder<ComparablePair<A extends Comparable<A>,B extends Comparable<B>>>