uk.ac.starlink.table
Class ConcatStarTable

java.lang.Object
  uk.ac.starlink.table.WrapperStarTable
      uk.ac.starlink.table.ConcatStarTable

All Implemented Interfaces:

StarTable

public class ConcatStarTable
extends WrapperStarTable

StarTable implementation which concatenates several tables together top-to-bottom. A (possibly blank) metadata table is supplied to define the column and table metadata for the result, and other data tables are added on one way or another, depending which constructor is used. The columns of each data table must be compatible with the columns of the metadata table, or the the data will not be included.

Since:

29 Mar 2004

Field Summary

Fields inherited from class uk.ac.starlink.table.WrapperStarTable

baseTable

Constructor Summary

ConcatStarTable(StarTable meta, Iterator tableIt)
Constructs a concatenated table from a metadata table and an iterator over data-bearing tables.

ConcatStarTable(StarTable meta, StarTable[] tables)
Constructs a concatenated table from a metadata table and an array of data-bearing tables.

Method Summary

static ColumnInfo[]	extendColumnTypes(ColumnInfo[] colInfos, StarTable[] tables) Assembles column metadata objects which are compatible between multiple tables.
Object	getCell(long irow, int icol) Returns the contents of a given table cell.
Object[]	getRow(long irow) Returns the contents of a given table row.
long	getRowCount() Returns the number of rows in this table, if known.
RowSequence	getRowSequence() Returns an object which can iterate over all the rows in the table sequentially.
boolean	isRandom() Indicates whether random access is provided by this table.

Methods inherited from class uk.ac.starlink.table.WrapperStarTable

checkedLongToInt, getBaseTable, getColumnAuxDataInfos, getColumnCount, getColumnInfo, getName, getParameterByName, getParameters, getURL, setName, setParameter, setURL, toString

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

ConcatStarTable

public ConcatStarTable(StarTable meta,
                       Iterator tableIt)

Constructs a concatenated table from a metadata table and an iterator over data-bearing tables. If any of the tables supplied by the iterator are incompatible with the metadata in meta a warning message is issued through the logging system and its rows are ignored.

Parameters:

meta - table supplying column and table metadata for this one; its row count is ignored and its data is never read

tableIt - iterator over constituent StarTables which taken in sequence supply the row data for this one

ConcatStarTable

public ConcatStarTable(StarTable meta,
                       StarTable[] tables)
                throws IOException

Constructs a concatenated table from a metadata table and an array of data-bearing tables. If any of tables are incompatible with the metadata in meta an IOException is thrown.

Parameters:

meta - table supplying column and table metadata for this one; its row count is ignored and its data is never read

tables - array of tables which taken in sequence supply the row data for this one

Throws:

IOException - if any of tables are not compatible with meta

Method Detail

getRowCount

public long getRowCount()

Description copied from interface: StarTable

Returns the number of rows in this table, if known. If the number of rows cannot be (easily) determined, a value of -1 will be returned.

Specified by:

getRowCount in interface StarTable

Overrides:

getRowCount in class WrapperStarTable

Returns:

the number of rows, or -1

getCell

public Object getCell(long irow,
                      int icol)
               throws IOException

Description copied from interface: StarTable

Returns the contents of a given table cell. The class of the returned object should be the same as, or a subclass of, the class returned by getColumnInfo(icol).getContentClass().

Specified by:

getCell in interface StarTable

Overrides:

getCell in class WrapperStarTable

Parameters:

irow - the index of the cell's row

icol - the index of the cell's column

Returns:

the contents of this cell

Throws:

IOException - if there is an error reading the data

getRow

public Object[] getRow(long irow)
                throws IOException

Description copied from interface: StarTable

Returns the contents of a given table row. The returned value is equivalent to an array formed of all the objects returned by getCell(irow,icol) for all the columns icol in sequence.

Specified by:

getRow in interface StarTable

Overrides:

getRow in class WrapperStarTable

Parameters:

irow - the index of the row to retrieve

Returns:

an array of the objects in each cell in row irow

Throws:

IOException - if there is an error reading the data

isRandom

public boolean isRandom()

Description copied from interface: StarTable

Indicates whether random access is provided by this table. Only if the result is true may the StarTable.getRow(long) and StarTable.getCell(long, int) methods be used.

Specified by:

isRandom in interface StarTable

Overrides:

isRandom in class WrapperStarTable

Returns:

true if table random access methods are available

getRowSequence

public RowSequence getRowSequence()
                           throws IOException

Description copied from interface: StarTable

Returns an object which can iterate over all the rows in the table sequentially.

Specified by:

getRowSequence in interface StarTable

Overrides:

getRowSequence in class WrapperStarTable

Returns:

an object providing sequential access to the table data

Throws:

IOException - if there is an error providing access

extendColumnTypes

public static ColumnInfo[] extendColumnTypes(ColumnInfo[] colInfos,
                                             StarTable[] tables)
                                      throws IOException

Assembles column metadata objects which are compatible between multiple tables. Nullability, array shape and element size are set to values which can accommodate all of the input tables. If column count or column data types are inconsistent, an IOException is thrown.

This utility method is not used by ConcatStarTable instances, but it may be useful when preparing metadata tables for use with the constructor.

Parameters:

colInfos - input column metadata objects

tables - list of tables with which columns must be compatible

Returns:

new array of new column metadata objects, based on input list

Throws:

IOException - if compatibility cannot be achieved