uk.ac.starlink.table

Class JoinStarTable

java.lang.Object

uk.ac.starlink.table.AbstractStarTable

uk.ac.starlink.table.JoinStarTable

All Implemented Interfaces:

Closeable, AutoCloseable, StarTable

public class JoinStarTable
extends AbstractStarTable

Joins a number of tables to produce a single combined table. The result consists of all the constituent tables side by side, so has a number of columns equal to the sum of the numbers of columns in all the constituent tables. The n^th row of this table is composed by appending the n^th rows of all the constituent tables together in sequence. The number of rows is equal to the smallest of all the number of rows in the constituent tables (typically they will all have the same number of rows). Random access is only available if it is available in all the constituent tables.

While this table is active, the columns that the constituent tables had at the time of its construction shouldn't change their characteristics in incompatible ways or disappear. It's OK to add new columns though.

Author:

Mark Taylor (Starlink)

Constructor Summary

Constructors

Constructor and Description
JoinStarTable(StarTable[] tables) Constructs a new JoinStarTable from a list of constituent tables.
JoinStarTable(StarTable[] tables, JoinFixAction[] fixCols) Constructs a new JoinStarTable from a list of constituent tables, optionally renaming duplicated column names.

Method Summary

Modifier and Type	Method and Description
void	close() Closes all the constituent tables.
Object	getCell(long irow, int icol) The AbstractStarTable implementation of this method throws an UnsupportedOperationException, since unless otherwise provided there is no random access.
int	getColumnCount() Returns the number of columns in this table.
ColumnInfo	getColumnInfo(int icol) Returns the object describing the data in a given column.
Object[]	getRow(long irow) The AbstractStarTable implementation of this method constructs a row by repeated invocation of AbstractStarTable.getCell(long, int).
RowAccess	getRowAccess() Returns an object which can provide random access to this table's data, if random access is implemented.
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.
List<StarTable>	getTables() Returns an unmodifiable list of the constituent tables providing the base data for this join table.
boolean	isRandom() The AbstractStarTable implementation of this method returns false.

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

checkedLongToInt, getColumnAuxDataInfos, getName, getParameters, getRowSplittable, getURL, setName, setParameters, setURL

Methods inherited from class java.lang.Object

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

Methods inherited from interface uk.ac.starlink.table.StarTable

getParameterByName, setParameter

Constructor Detail

JoinStarTable

public JoinStarTable(StarTable[] tables,
                     JoinFixAction[] fixCols)

Constructs a new JoinStarTable from a list of constituent tables, optionally renaming duplicated column names.

Parameters:

tables - array of constituent table objects providing the data and metadata for a new joined table

fixCols - actions to be taken in modifying column names from the originals (may be null for no action)

JoinStarTable

public JoinStarTable(StarTable[] tables)

Constructs a new JoinStarTable from a list of constituent tables. No column renaming is done.

Parameters:

tables - array of constituent table objects providing the data and metadata for a new joined table

Method Detail

getTables

public List<StarTable> getTables()

Returns an unmodifiable list of the constituent tables providing the base data for this join table.

Returns:

list of tables

getColumnCount

public int getColumnCount()

Description copied from interface: StarTable

Returns the number of columns in this table.

Specified by:

getColumnCount in interface StarTable

Specified by:

getColumnCount in class AbstractStarTable

Returns:

the number of columns

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

Specified by:

getRowCount in class AbstractStarTable

Returns:

the number of rows, or -1

getColumnInfo

public ColumnInfo getColumnInfo(int icol)

Description copied from interface: StarTable

Returns the object describing the data in a given column.

Specified by:

getColumnInfo in interface StarTable

Specified by:

getColumnInfo in class AbstractStarTable

Parameters:

icol - the column for which header information is required

Returns:

a ValueInfo object for column icol

isRandom

public boolean isRandom()

Description copied from class: AbstractStarTable

The AbstractStarTable implementation of this method returns false.

Specified by:

isRandom in interface StarTable

Overrides:

isRandom in class AbstractStarTable

Returns:

true if table random access methods are available

getCell

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

Description copied from class: AbstractStarTable

The AbstractStarTable implementation of this method throws an UnsupportedOperationException, since unless otherwise provided there is no random access.

Specified by:

getCell in interface StarTable

Overrides:

getCell in class AbstractStarTable

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 class: AbstractStarTable

The AbstractStarTable implementation of this method constructs a row by repeated invocation of AbstractStarTable.getCell(long, int).

Specified by:

getRow in interface StarTable

Overrides:

getRow in class AbstractStarTable

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

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. Each such returned object is safe for use within a single thread, but not in general from multiple threads concurrently.

Specified by:

getRowSequence in interface StarTable

Specified by:

getRowSequence in class AbstractStarTable

Returns:

new RowSequence

Throws:

IOException - if there is an error providing access

getRowAccess

public RowAccess getRowAccess()
                       throws IOException

Description copied from interface: StarTable

Returns an object which can provide random access to this table's data, if random access is implemented. Each such returned object is safe for use within a single thread, but not in general from multiple threads concurrently.

Specified by:

getRowAccess in interface StarTable

Overrides:

getRowAccess in class AbstractStarTable

Returns:

new RowAccess

Throws:

IOException - if there is an error setting up access

close

public void close()
           throws IOException

Closes all the constituent tables.

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

Specified by:

close in interface StarTable

Overrides:

close in class AbstractStarTable

Throws:

IOException