Package uk.ac.starlink.table
Class ColumnData
java.lang.Object
uk.ac.starlink.table.ColumnData
- Direct Known Subclasses:
ArrayColumn
,BlankColumn
,ConstantColumn
,WrapperColumn
A column which can supply and possibly store cells in array-like storage
as well as supply column metadata.
Note there is nothing in this class which describes the number of
elements it contains (length of the column). Columns are intended to be
managed by tables, and it is the table which should keep track of
this information.
- Author:
- Mark Taylor (Starlink)
-
Constructor Summary
ConstructorsConstructorDescriptionConstructs a new ColumnData with no metadata.ColumnData
(ColumnInfo colinfo) Constructs a new ColumnData with metadata supplied by a given ColumnInfo object.ColumnData
(ValueInfo base) Performs ColumnData initialisation based on template ValueInfo object. -
Method Summary
Modifier and TypeMethodDescriptionReturns the ColumnInfo which provides the metadata for this column.boolean
Indicates whether this object can store values.abstract Object
readValue
(long irow) Returns the value stored at a given row in this column.void
setColumnInfo
(ColumnInfo colinfo) Sets the ColumnInfo which provides the metadata for this column.void
storeValue
(long irow, Object val) Stores a given value in a given row for this column.
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Constructor Details
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ColumnData
public ColumnData()Constructs a new ColumnData with no metadata. -
ColumnData
Constructs a new ColumnData with metadata supplied by a given ColumnInfo object.- Parameters:
colinfo
- the column metadata
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ColumnData
Performs ColumnData initialisation based on template ValueInfo object.- Parameters:
base
- template
-
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Method Details
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getColumnInfo
Returns the ColumnInfo which provides the metadata for this column.- Returns:
- the column metadata
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setColumnInfo
Sets the ColumnInfo which provides the metadata for this column.- Parameters:
colinfo
- the column metadata
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readValue
Returns the value stored at a given row in this column.- Parameters:
irow
- the row from which to retrieve the value- Returns:
- the value stored at irow
- Throws:
IOException
- if there is some problem reading
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storeValue
Stores a given value in a given row for this column. Will only work if the isWritable method returns true. The implementation in the ColumnData class throws an UnsupportedOperationException.- Parameters:
irow
- the row to store it inval
- the object to store- Throws:
UnsupportedOperationException
- if !isWritable()
NullPointerException
- if val==null and this column is not nullableArrayStoreException
- if val is not compatible with the content class of this columnIOException
- if there is some problem writing
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isWritable
public boolean isWritable()Indicates whether this object can store values. The implementation in the ColumnData class returns false- Returns:
- true iff
storeValue(long, java.lang.Object)
can be used
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