接口 com.aliyun.odps.io.WritableComparable
的使用

使用WritableComparable的程序包

程序包	说明
com.aliyun.odps.io	ODPS中使用的Writable数据类型，目前只有Graph作业需要使用

com.aliyun.odps.io中WritableComparable的使用

com.aliyun.odps.io中WritableComparable的子接口

限定符和类型	接口和说明
interface	InputBlobWritable InputBlobWritable表示ODPS表或分区中列类型为blob的输入接口.
interface	OutputBlobWritable OutputBlobWritable表示ODPS表或分区中列类型为blob的输出接口, 该接口只能用于 com.aliyun.odps.mapreduce.Reducer向 com.aliyun.odps.Record 中写入blob类型的列.

实现WritableComparable的com.aliyun.odps.io中的类

限定符和类型	类和说明
class	BooleanWritable BooleanWritable 提供了 boolean 的 Writable 和 WritableComparable 的实现
class	BytesWritable BytesWritable 提供了 byte[] 的 Writable 和 WritableComparable 的实现.
class	DatetimeWritable DatetimeWritable 提供了 datetime 的 Writable 和 WritableComparable 的实现
class	DoubleWritable DoubleWritable 提供了 double 的 Writable 和 WritableComparable 的实现
class	IntWritable IntWritable 提供了 int 的 Writable 和 WritableComparable 的实现
class	LongWritable LongWritable 提供了 long 的 Writable 和 WritableComparable 的实现
class	NullWritable NullWritable 提供了 null （空值）的 Writable 和 WritableComparable 的实现.
class	Text Text 提供了字符串的 Writable 和 WritableComparable 的实现.
class	Tuple Tuple 是 Writable 对象的有序集.

返回WritableComparable的com.aliyun.odps.io中的方法

限定符和类型	方法和说明
WritableComparable	SortedMapWritable.firstKey()
WritableComparable	SortedMapWritable.lastKey()
WritableComparable	WritableComparator.newKey() 新建一个新的 WritableComparable 对象.

返回变量类型为WritableComparable的类型的com.aliyun.odps.io中的方法

限定符和类型	方法和说明
Comparator<? super WritableComparable>	SortedMapWritable.comparator()
Set<Map.Entry<WritableComparable,Writable>>	SortedMapWritable.entrySet()
Class<? extends WritableComparable>	WritableComparator.getKeyClass() 返回待比较的 WritableComparable 实现类
SortedMap<WritableComparable,Writable>	SortedMapWritable.headMap(WritableComparable toKey)
Set<WritableComparable>	SortedMapWritable.keySet()
SortedMap<WritableComparable,Writable>	SortedMapWritable.subMap(WritableComparable fromKey, WritableComparable toKey)
SortedMap<WritableComparable,Writable>	SortedMapWritable.tailMap(WritableComparable fromKey)

参数类型为WritableComparable的com.aliyun.odps.io中的方法

限定符和类型	方法和说明
int	LongWritable.DecreasingComparator.compare(WritableComparable a, WritableComparable b)
int	LongWritable.DecreasingComparator.compare(WritableComparable a, WritableComparable b)
int	DatetimeWritable.DecreasingComparator.compare(WritableComparable a, WritableComparable b)
int	DatetimeWritable.DecreasingComparator.compare(WritableComparable a, WritableComparable b)
int	WritableComparator.compare(WritableComparable a, WritableComparable b) 比较两个 WritableComparable 对象.
int	WritableComparator.compare(WritableComparable a, WritableComparable b) 比较两个 WritableComparable 对象.
SortedMap<WritableComparable,Writable>	SortedMapWritable.headMap(WritableComparable toKey)
Writable	SortedMapWritable.put(WritableComparable key, Writable value)
SortedMap<WritableComparable,Writable>	SortedMapWritable.subMap(WritableComparable fromKey, WritableComparable toKey)
SortedMap<WritableComparable,Writable>	SortedMapWritable.subMap(WritableComparable fromKey, WritableComparable toKey)
SortedMap<WritableComparable,Writable>	SortedMapWritable.tailMap(WritableComparable fromKey)

类型变量类型为WritableComparable的com.aliyun.odps.io中的方法参数

限定符和类型	方法和说明
static WritableComparator	WritableComparator.get(Class<? extends WritableComparable> c) 此静态方法用于获取为类型 c 注册的 WritableComparator 实现.
void	SortedMapWritable.putAll(Map<? extends WritableComparable,? extends Writable> t)