目录一、直接使用 == null(最基础)二、Objects.isNull ()(JDK 8+)三、Objects.nonNull ()(JDK 8+)四、Optional 类(JDK 8+)五、Apache Commons Lang(第三方库)六、StringUtils(Apache Commons Lang)
I need to delete all the lines on a subplot, to then redr开发者_如何学Pythonaw them (i\'m making a redraw function to be used when i add/remove some lines)