question: @ Override public Range findDomainBounds ( XYDataset dataset ) { ParamChecks . nullNotPermitted ( dataset , "dataset" ) ; double minimum = Double . POSITIVE_INFINITY ; double maximum = Double . NEGATIVE_INFINITY ; int seriesCount = dataset . getSeriesCount ( ) ; double lvalue ; double uvalue ; if ( dataset instanceof VectorXYDataset ) { VectorXYDataset vdataset = ( VectorXYDataset ) dataset ; for ( int series = 0 ; series < seriesCount ; series ++ ) { int itemCount = dataset . getItemCount ( series ) ; for ( int item = 0 ; item < itemCount ; item ++ ) { double delta = vdataset . getVectorXValue ( series , item ) ; if ( delta < 0.0 ) { uvalue = vdataset . getXValue ( series , item ) ; lvalue = uvalue + delta ; } else { lvalue = vdataset . getXValue ( series , item ) ; uvalue = lvalue + delta ; } minimum = Math . min ( minimum , lvalue ) ; maximum = Math . max ( maximum , uvalue ) ; } } } else { for ( int series = 0 ; series < seriesCount ; series ++ ) { int itemCount = dataset . getItemCount ( series ) ; for ( int item = 0 ; item < itemCount ; item ++ ) { lvalue = dataset . getXValue ( series , item ) ; uvalue = lvalue ; minimum = Math . min ( minimum , lvalue ) ; maximum = Math . max ( maximum , uvalue ) ; } } } if ( minimum > maximum ) { return null ; } else { return new Range ( minimum , maximum ) ; } }
target:  Returns the lower and upper bounds (range) of the x-values in the specified dataset.