Package uk.ac.starlink.table
Class ReaderRowSequence
java.lang.Object
uk.ac.starlink.table.ReaderRowSequence
- All Implemented Interfaces:
Closeable
,AutoCloseable
,RowData
,RowSequence
,uk.ac.starlink.util.Sequence
Partial implementation of
RowSequence
suitable for subclassing
by classes which can read a row at a time and don't know when the
row stream will come to an end.
Concrete subclasses have to implement the readRow()
method.
They may also want to override close()
.- Author:
- Mark Taylor (Starlink)
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Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionvoid
close()
TheReaderRowSequence
implementation does nothing.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.protected abstract Object[]
readRow()
Acquires the next row of objects from the input stream.
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Constructor Details
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ReaderRowSequence
public ReaderRowSequence()
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Method Details
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readRow
Acquires the next row of objects from the input stream. When there are no more rows to read this method must returnnull
; note it should not throw an exception to indicate this fact. Otherwise it must return an array of objects representing the row content for the next row.- Returns:
- the next row, or
null
if there are no more - Throws:
IOException
- if there is trouble reading the data
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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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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
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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
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close
TheReaderRowSequence
implementation does nothing.- Specified by:
close
in interfaceAutoCloseable
- Specified by:
close
in interfaceCloseable
- Specified by:
close
in interfaceRowSequence
- Throws:
IOException
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