NullpointerException when converting String to double in java

Question

I have an html form which contains a String which I need to convert into a double . Then store it in an MS Access database. I tried using:

Double d = Double.parseDouble(String);

But it is throwing a NullpointerException. Can anyone explain why?

Answer 1

看一下API，发现如果参数为null ，则Double.parseDouble抛出NullPointerException 。