uk.ac.starlink.table

## Class BlankColumn

- java.lang.Object
- - uk.ac.starlink.table.ColumnData
  - - uk.ac.starlink.table.BlankColumn

-     public class BlankColumn
      extends ColumnData

  Represents a column with metadata but no data. Every cell returns null, and is not writable.
  Since:
    28 Oct 2004

- - ### Constructor Summary

    Constructors
    Constructor and Description
    `BlankColumn(ColumnInfo colinfo)` Constructs a new column based on a given column metadata object.

  - ### Method Summary

    All Methods Instance Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `java.lang.Object` | `readValue(long irow)` Returns column value, which is always null.

    - ### Methods inherited from class uk.ac.starlink.table.ColumnData

      `getColumnInfo, isWritable, setColumnInfo, storeValue`

    - ### Methods inherited from class java.lang.Object

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

- - ### Constructor Detail

    - #### BlankColumn

          public BlankColumn(ColumnInfo colinfo)

      Constructs a new column based on a given column metadata object.
      Parameters:
        `colinfo` - metadata for column

  - ### Method Detail

    - #### readValue

          public java.lang.Object readValue(long irow)

      Returns column value, which is always null.
      Specified by:
        `readValue` in class `ColumnData`
      Parameters:
        `irow` - row index
      Returns:
        null