uk.ac.starlink.table

Class ColumnInfo

java.lang.Object

uk.ac.starlink.table.DefaultValueInfo

uk.ac.starlink.table.ColumnInfo

All Implemented Interfaces:

ValueInfo

public class ColumnInfo
extends DefaultValueInfo

Contains information about a table column. This really does the same thing as its superclass, DefaultValueInfo, but for historical reasons it contains some additional methods for access to the auxiliary metadata items. In earlier versions of the library, columns were allowed to store auxiliary metadata and non-column items (like table parameters) were not, but now they have the same capabilities.

Constructor Summary

Constructors

Constructor and Description
ColumnInfo(java.lang.String name) Constructs a ColumnInfo object.
ColumnInfo(java.lang.String name, java.lang.Class<?> contentClass, java.lang.String description) Constructs a new ColumnInfo object with a given name, class and description.
ColumnInfo(ValueInfo base) Constructs a new ColumnInfo based on a ValueInfo object.

Method Summary

Modifier and Type	Method and Description
DescribedValue	getAuxDatum(ValueInfo vinfo) Gets an item of auxiliary metadata from its specification.
<T> T	getAuxDatumValue(ValueInfo vinfo, java.lang.Class<T> clazz) Gets the value of an item of auxiliary metadata using its specification, requiring a particular return type.
<T> T	getAuxDatumValueByName(java.lang.String name, java.lang.Class<T> clazz) Gets the value of an item of auxiliary metadata by its name, requiring a particular return type.

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

formatClass, formatShape, formatValue, generalise, getAuxData, getContentClass, getDescription, getDomainMappers, getElementSize, getName, getShape, getUCD, getUnitString, getUtype, getXtype, isArray, isNullable, setAuxData, setContentClass, setDescription, setDomainMappers, setElementSize, setName, setNullable, setShape, setUCD, setUnitString, setUtype, setXtype, toString, unformatShape, unformatString

Methods inherited from class java.lang.Object

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

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

getAuxDatumByName, setAuxDatum

Constructor Detail

ColumnInfo

public ColumnInfo(java.lang.String name)

Constructs a ColumnInfo object.

Parameters:

name - the name of the column

ColumnInfo

public ColumnInfo(ValueInfo base)

Constructs a new ColumnInfo based on a ValueInfo object. All attributes are copied from the template to the new object.

Parameters:

base - the template ValueInfo

ColumnInfo

public ColumnInfo(java.lang.String name,
                  java.lang.Class<?> contentClass,
                  java.lang.String description)

Constructs a new ColumnInfo object with a given name, class and description.

Parameters:

name - the name applying to described values

contentClass - the class of which described values should be instances

description - a textual description of the described values

Method Detail

getAuxDatum

public DescribedValue getAuxDatum(ValueInfo vinfo)

Gets an item of auxiliary metadata from its specification. Currently this just calls getAuxDatumByName(vinfo.getName()), but may be revised in future to match on other attributes.

Parameters:

vinfo - the data item to match

Returns:

a DescribedValue object representing the auxiliary metadata item matching vinfo for this column, or null if none exists

getAuxDatumValue

public <T> T getAuxDatumValue(ValueInfo vinfo,
                              java.lang.Class<T> clazz)

Gets the value of an item of auxiliary metadata using its specification, requiring a particular return type. This convenience method works like getAuxDatum(uk.ac.starlink.table.ValueInfo) but returns a non-null value only if the named item exists and if its value is an instance of the given type clazz.

Parameters:

vinfo - the data item to match

clazz - required return type

Returns:

value of the auxiliary metadata item matching vinfo for this column if it exists and is an instance of clazz or one of its subtypes, otherwise null

getAuxDatumValueByName

public <T> T getAuxDatumValueByName(java.lang.String name,
                                    java.lang.Class<T> clazz)

Gets the value of an item of auxiliary metadata by its name, requiring a particular return type. This convenience method works like ValueInfo.getAuxDatumByName(java.lang.String), but returns a non-null value only if the named item exists, and if its value is an instance of the given type clazz.

Parameters:

name - the name of an auxiliary metadata item

clazz - required return type

Returns:

value of the auxiliary metadata item matching vinfo for this column if it exists and is an instance of clazz or one of its subtypes, otherwise null