ColumnObserver (gephi 0.9.3 API)

```
public interface ColumnObserver
```
Observer over a column to monitor changes in the attributes values.
Column observer can be used to periodically monitor changes made to a column. This scenario is common is multi-threaded applications where a thread is responsible to take action when something has changed in the column's data.
Column observer users should periodically call the hasColumnChanged() method to check the status. Each call resets the observer so if the method returns true and the table doesn't change after that it will return false next time.
This observer monitors all the rows for this column and consider something has changed when an element's value for this column has been changed.
Observers should be destroyed when not needed anymore. A new observer can be obtained from the Column.

See Also:

Column

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method	Description
`void`	`destroy()`	Destroys this observer.
`Column`	`getColumn()`	Gets the column this observer belongs to.
`ColumnDiff`	`getDiff()`	Gets the column difference.
`boolean`	`hasColumnChanged()`	Returns true if the column has changed.
`boolean`	`isDestroyed()`	Returns true if this observer has been destroyed.

- Method Detail
  - hasColumnChanged
```
boolean hasColumnChanged()
```
    Returns true if the column has changed.
    
    Returns:
    
    true if changed, false otherwise
  - getDiff
```
ColumnDiff getDiff()
```
    Gets the column difference.
    
    Returns:
    
    the column diff
  - getColumn
```
Column getColumn()
```
    Gets the column this observer belongs to.
    
    Returns:
    
    the table
  - destroy
```
void destroy()
```
    Destroys this observer.
  - isDestroyed
```
boolean isDestroyed()
```
    Returns true if this observer has been destroyed.
    
    Returns:
    
    true if destroyed, false otherwise