DoubleColumnInterpreter (Apache HBase

java.lang.Object
- org.apache.hadoop.hbase.coprocessor.ColumnInterpreter<Double,Double,HBaseProtos.EmptyMsg,HBaseProtos.DoubleMsg,HBaseProtos.DoubleMsg>
- - org.apache.hadoop.hbase.client.coprocessor.DoubleColumnInterpreter

```
@InterfaceAudience.LimitedPrivate(value="Coprocesssor")
 @InterfaceStability.Evolving
public class DoubleColumnInterpreter
extends ColumnInterpreter<Double,Double,HBaseProtos.EmptyMsg,HBaseProtos.DoubleMsg,HBaseProtos.DoubleMsg>
```
a concrete column interpreter implementation. The cell value is a Double value and its promoted data type is also a Double value. For computing aggregation function, this class is used to find the datatype of the cell value. Client is supposed to instantiate it and passed along as a parameter. See TestDoubleColumnInterpreter methods for its sample usage. Its methods handle null arguments gracefully.

构造器概要

构造器
构造器和说明

DoubleColumnInterpreter()

构造器
构造器和说明
`DoubleColumnInterpreter()`

方法概要

所有方法实例方法具体方法
限定符和类型	方法和说明
`Double`	`add(Double d1, Double d2)`
`Double`	`castToCellType(Double d)` The response message comes as type S.
`Double`	`castToReturnType(Double o)` provides casting opportunity between the data types.
`int`	`compare(Double d1, Double d2)` This takes care if either of arguments are null. returns 0 if they are equal or both are null; > 0 if l1 > l2 or l1 is not null and l2 is null.
`double`	`divideForAvg(Double d1, Long l2)` used for computing average of <S> data values.
`Double`	`getCellValueFromProto(HBaseProtos.DoubleMsg q)` This method gets the PB message corresponding to the cell type
`Double`	`getMaxValue()` returns the maximum value for this type T
`Double`	`getMinValue()`
`Double`	`getPromotedValueFromProto(HBaseProtos.DoubleMsg r)` This method gets the promoted type from the proto message
`HBaseProtos.DoubleMsg`	`getProtoForCellType(Double t)` This method gets the PB message corresponding to the cell type
`HBaseProtos.DoubleMsg`	`getProtoForPromotedType(Double s)` This method gets the PB message corresponding to the promoted type
`HBaseProtos.EmptyMsg`	`getRequestData()` This method should return any additional data that is needed on the server side to construct the ColumnInterpreter.
`Double`	`getValue(byte[] colFamily, byte[] colQualifier, Cell c)`
`Double`	`increment(Double o)`
`void`	`initialize(HBaseProtos.EmptyMsg msg)` This method should initialize any field(s) of the ColumnInterpreter with a parsing of the passed message bytes (used on the server side).
`Double`	`multiply(Double d1, Double d2)`

从类继承的方法 java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- 构造器详细资料
  - DoubleColumnInterpreter
```
public DoubleColumnInterpreter()
```
- 方法详细资料
  - getValue
```
public Double getValue(byte[] colFamily,
                       byte[] colQualifier,
                       Cell c)
                throws IOException
```
    指定者:
    
    getValue 在类中 ColumnInterpreter<Double,Double,HBaseProtos.EmptyMsg,HBaseProtos.DoubleMsg,HBaseProtos.DoubleMsg>
    
    返回:
    
    value of type T
    
    抛出:
    
    IOException
  - add
```
public Double add(Double d1,
                  Double d2)
```
    指定者:
    
    add 在类中 ColumnInterpreter<Double,Double,HBaseProtos.EmptyMsg,HBaseProtos.DoubleMsg,HBaseProtos.DoubleMsg>
    
    返回:
    
    sum or non null value among (if either of them is null); otherwise returns a null.
  - compare
```
public int compare(Double d1,
                   Double d2)
```
    从类复制的说明: ColumnInterpreter
    This takes care if either of arguments are null. returns 0 if they are equal or both are null;
    - > 0 if l1 > l2 or l1 is not null and l2 is null.
    - < 0 if l1 < l2 or l1 is null and l2 is not null.
    指定者:
    
    compare 在类中 ColumnInterpreter<Double,Double,HBaseProtos.EmptyMsg,HBaseProtos.DoubleMsg,HBaseProtos.DoubleMsg>
  - getMaxValue
```
public Double getMaxValue()
```
    从类复制的说明: ColumnInterpreter
    
    returns the maximum value for this type T
    
    指定者:
    
    getMaxValue 在类中 ColumnInterpreter<Double,Double,HBaseProtos.EmptyMsg,HBaseProtos.DoubleMsg,HBaseProtos.DoubleMsg>
    
    返回:
    
    max
  - increment
```
public Double increment(Double o)
```
    指定者:
    
    increment 在类中 ColumnInterpreter<Double,Double,HBaseProtos.EmptyMsg,HBaseProtos.DoubleMsg,HBaseProtos.DoubleMsg>
    
    返回:
    
    increment
  - multiply
```
public Double multiply(Double d1,
                       Double d2)
```
    指定者:
    
    multiply 在类中 ColumnInterpreter<Double,Double,HBaseProtos.EmptyMsg,HBaseProtos.DoubleMsg,HBaseProtos.DoubleMsg>
    
    返回:
    
    multiplication
  - getMinValue
```
public Double getMinValue()
```
    指定者:
    
    getMinValue 在类中 ColumnInterpreter<Double,Double,HBaseProtos.EmptyMsg,HBaseProtos.DoubleMsg,HBaseProtos.DoubleMsg>
  - divideForAvg
```
public double divideForAvg(Double d1,
                           Long l2)
```
    从类复制的说明: ColumnInterpreter
    
    used for computing average of <S> data values. Not providing the divide method that takes two <S> values as it is not needed as of now.
    
    指定者:
    
    divideForAvg 在类中 ColumnInterpreter<Double,Double,HBaseProtos.EmptyMsg,HBaseProtos.DoubleMsg,HBaseProtos.DoubleMsg>
    
    返回:
    
    Average
  - castToReturnType
```
public Double castToReturnType(Double o)
```
    从类复制的说明: ColumnInterpreter
    
    provides casting opportunity between the data types.
    
    指定者:
    
    castToReturnType 在类中 ColumnInterpreter<Double,Double,HBaseProtos.EmptyMsg,HBaseProtos.DoubleMsg,HBaseProtos.DoubleMsg>
    
    返回:
    
    cast
  - castToCellType
```
public Double castToCellType(Double d)
```
    从类复制的说明: ColumnInterpreter
    
    The response message comes as type S. This will convert/cast it to T. In some sense, performs the opposite of ColumnInterpreter.castToReturnType(Object)
    
    指定者:
    
    castToCellType 在类中 ColumnInterpreter<Double,Double,HBaseProtos.EmptyMsg,HBaseProtos.DoubleMsg,HBaseProtos.DoubleMsg>
    
    返回:
    
    cast
  - getRequestData
```
public HBaseProtos.EmptyMsg getRequestData()
```
    从类复制的说明: ColumnInterpreter
    
    This method should return any additional data that is needed on the server side to construct the ColumnInterpreter. The server will pass this to the ColumnInterpreter.initialize(P) method. If there is no ColumnInterpreter specific data (for e.g., LongColumnInterpreter) then null should be returned.
    
    指定者:
    
    getRequestData 在类中 ColumnInterpreter<Double,Double,HBaseProtos.EmptyMsg,HBaseProtos.DoubleMsg,HBaseProtos.DoubleMsg>
    
    返回:
    
    the PB message
  - initialize
```
public void initialize(HBaseProtos.EmptyMsg msg)
```
    从类复制的说明: ColumnInterpreter
    
    This method should initialize any field(s) of the ColumnInterpreter with a parsing of the passed message bytes (used on the server side).
    
    指定者:
    
    initialize 在类中 ColumnInterpreter<Double,Double,HBaseProtos.EmptyMsg,HBaseProtos.DoubleMsg,HBaseProtos.DoubleMsg>
  - getProtoForCellType
```
public HBaseProtos.DoubleMsg getProtoForCellType(Double t)
```
    从类复制的说明: ColumnInterpreter
    
    This method gets the PB message corresponding to the cell type
    
    指定者:
    
    getProtoForCellType 在类中 ColumnInterpreter<Double,Double,HBaseProtos.EmptyMsg,HBaseProtos.DoubleMsg,HBaseProtos.DoubleMsg>
    
    返回:
    
    the PB message for the cell-type instance
  - getProtoForPromotedType
```
public HBaseProtos.DoubleMsg getProtoForPromotedType(Double s)
```
    从类复制的说明: ColumnInterpreter
    
    This method gets the PB message corresponding to the promoted type
    
    指定者:
    
    getProtoForPromotedType 在类中 ColumnInterpreter<Double,Double,HBaseProtos.EmptyMsg,HBaseProtos.DoubleMsg,HBaseProtos.DoubleMsg>
    
    返回:
    
    the PB message for the promoted-type instance
  - getPromotedValueFromProto
```
public Double getPromotedValueFromProto(HBaseProtos.DoubleMsg r)
```
    从类复制的说明: ColumnInterpreter
    
    This method gets the promoted type from the proto message
    
    指定者:
    
    getPromotedValueFromProto 在类中 ColumnInterpreter<Double,Double,HBaseProtos.EmptyMsg,HBaseProtos.DoubleMsg,HBaseProtos.DoubleMsg>
    
    返回:
    
    the promoted-type instance from the PB message
  - getCellValueFromProto
```
public Double getCellValueFromProto(HBaseProtos.DoubleMsg q)
```
    从类复制的说明: ColumnInterpreter
    
    This method gets the PB message corresponding to the cell type
    
    指定者:
    
    getCellValueFromProto 在类中 ColumnInterpreter<Double,Double,HBaseProtos.EmptyMsg,HBaseProtos.DoubleMsg,HBaseProtos.DoubleMsg>
    
    返回:
    
    the cell-type instance from the PB message

类 DoubleColumnInterpreter

构造器概要

方法概要

从类继承的方法 java.lang.Object

构造器详细资料

DoubleColumnInterpreter

方法详细资料

getValue

add

compare

getMaxValue

increment

multiply

getMinValue

divideForAvg

castToReturnType

castToCellType

getRequestData

initialize

getProtoForCellType

getProtoForPromotedType

getPromotedValueFromProto

getCellValueFromProto