question: private boolean verifyValueRangeUpperBoundInput ( JComponent input ) { JTextField textField = ( JTextField ) input ; String inputString = textField . getText ( ) ; try { double valueUpperBound ; if ( inputString . startsWith ( "-" ) ) { valueUpperBound = Double . parseDouble ( inputString . substring ( 1 ) ) ; valueUpperBound = - valueUpperBound ; } else { valueUpperBound = Double . parseDouble ( inputString ) ; } } catch ( NumberFormatException e ) { textField . setForeground ( Color . RED ) ; return false ; } textField . setForeground ( Color . BLACK ) ; return true ; }
target:  Verify that the height value is correct.