BlankColumn (Starjava Table API)

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

Author:

Mark Taylor (Starlink)

- Constructor Summary
  
  Constructors
  Constructor 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 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