Class SequentialRowSplittable
- All Implemented Interfaces:
Closeable
,AutoCloseable
,RowData
,RowSequence
,RowSplittable
,uk.ac.starlink.util.Sequence
,uk.ac.starlink.util.Splittable<RowSplittable>
- Since:
- 4 Aug 2020
- Author:
- Mark Taylor
-
Constructor Summary
ConstructorsConstructorDescriptionConstructs a RowSplittable from a row sequence, with an indeterminate number of rows.SequentialRowSplittable
(RowSequence rseq, long nrow) Constructs a RowSplittable from a RowSequence and a given number of rows.SequentialRowSplittable
(StarTable table) Convenience constructor, constructs a RowSplittable from a table. -
Method Summary
Modifier and TypeMethodDescriptionvoid
close()
Indicates that this sequence will not be required any more.getCell
(int icol) Returns the contents of a cell in the current row.Object[]
getRow()
Returns the contents of the current table row, as an array with the same number of elements as there are columns in this table.boolean
next()
Attempts to advance the current row to the next one.rowIndex()
Returns a supplier for the index of the row currently being processed, if possible.split()
long
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Constructor Details
-
SequentialRowSplittable
Convenience constructor, constructs a RowSplittable from a table.- Parameters:
table
- table- Throws:
IOException
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SequentialRowSplittable
Constructs a RowSplittable from a row sequence, with an indeterminate number of rows.- Parameters:
rseq
- sequence
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SequentialRowSplittable
Constructs a RowSplittable from a RowSequence and a given number of rows.- Parameters:
rseq
- row sequencenrow
- row count, used as return value ofsplittableSize
; may be -1 if not known
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Method Details
-
splittableSize
public long splittableSize()- Specified by:
splittableSize
in interfaceuk.ac.starlink.util.Splittable<RowSplittable>
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split
- Specified by:
split
in interfaceuk.ac.starlink.util.Splittable<RowSplittable>
-
next
Description copied from interface:RowSequence
Attempts to advance the current row to the next one. Iftrue
is returned the attempt has been successful, and iffalse
is returned there are no more rows in this sequence. Since the initial position of a RowSequence is before the first row, this method must be called before current row data can be accessed using theRowSequence.getCell(int)
orRowSequence.getRow()
methods.- Specified by:
next
in interfaceRowSequence
- Specified by:
next
in interfaceuk.ac.starlink.util.Sequence
- Returns:
true
iff this sequence has been advanced to the next row- Throws:
IOException
- if there is some error
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rowIndex
Description copied from interface:RowSplittable
Returns a supplier for the index of the row currently being processed, if possible. The row index is a global value; when accessing the first row of a top-level RowSplittable, the value returned by this supplier should be the first index in the table. But for objects resulting from splitting a top-level instance into sub-instances, the return value should reflect the index in the original sequence of rows; each index should be returned from only one of the splittables resulting from splitting a top-level instance.Typically, the row index will start at 0 and increment for each row, but the numbering may be different depending on the requirements of the implementation or usage.
Before the
RowSequence.next()
method has been called, the return value will be one less than the first row index. AfterRowSequence.next
has returned false, the value is undefined.Depending on the implementation, it may not be possible to determine the row index (for instance if the sequence is split into sub-splittables of unknown size). In such cases, this method returns null. The null-ness of the return value must be the same for all instances of the splittable hierarchy for a given sequence, so don't return a non-null value for the first splittable and then null values for some or all of its children.
- Specified by:
rowIndex
in interfaceRowSplittable
- Returns:
- supplier for the globally-referenced row index value of the current row of this sequence, or null
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getCell
Description copied from interface:RowSequence
Returns the contents of a cell in the current row. The class of the returned object should be the same as, or a subclass of, the class returned bygetColumnInfo(icol).getContentClass()
. An unchecked exception will be thrown if there is no current row (next
has not yet been called).- Specified by:
getCell
in interfaceRowData
- Specified by:
getCell
in interfaceRowSequence
- Parameters:
icol
- column index- Returns:
- the contents of cell
icol
in the current row - Throws:
IOException
- if there is an error reading the data
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getRow
Description copied from interface:RowSequence
Returns the contents of the current table row, as an array with the same number of elements as there are columns in this table. An unchecked exception will be thrown if there is no current row (next
has not yet been called).- Specified by:
getRow
in interfaceRowData
- Specified by:
getRow
in interfaceRowSequence
- Returns:
- an array of the objects in each cell in row
irow
- Throws:
IOException
- if there is an error reading the data
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close
Description copied from interface:RowSequence
Indicates that this sequence will not be required any more. This should release resources associated with this object. The effect of calling any of the other methods following aclose
is undefined.- Specified by:
close
in interfaceAutoCloseable
- Specified by:
close
in interfaceCloseable
- Specified by:
close
in interfaceRowSequence
- Throws:
IOException
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