question: @ Override public void addUndoPoint ( ) { File tempFile ; ObjectOutputStream oos ; if ( ! isUndoEnabled ( ) ) { return ; } if ( getInstances ( ) != null ) { try { tempFile = File . createTempFile ( "arffviewer" , null ) ; tempFile . deleteOnExit ( ) ; oos = new ObjectOutputStream ( new BufferedOutputStream ( new FileOutputStream ( tempFile ) ) ) ; oos . writeObject ( getInstances ( ) ) ; oos . flush ( ) ; oos . close ( ) ; m_UndoList . add ( tempFile ) ; } catch ( Exception e ) { e . printStackTrace ( ) ; } } }
target:  adds an undo point to the undo history, if the undo support is enabled