question: @ Override public Range findRangeBounds ( CategoryDataset dataset ) { if ( dataset == null ) { return null ; } boolean allItemsNull = true ; double minimum = 0.0 ; double maximum = 0.0 ; int columnCount = dataset . getColumnCount ( ) ; for ( int row = 0 ; row < dataset . getRowCount ( ) ; row ++ ) { double runningTotal = 0.0 ; for ( int column = 0 ; column <= columnCount - 1 ; column ++ ) { Number n = dataset . getValue ( row , column ) ; if ( n != null ) { allItemsNull = false ; double value = n . doubleValue ( ) ; if ( column == columnCount - 1 ) { runningTotal = value ; } else { runningTotal = runningTotal + value ; } minimum = Math . min ( minimum , runningTotal ) ; maximum = Math . max ( maximum , runningTotal ) ; } } } if ( ! allItemsNull ) { return new Range ( minimum , maximum ) ; } else { return null ; } }
target:  Returns the range of values the renderer requires to display all the items from the specified dataset.