HashMaps and Null values?

Question

How do you pass in null values into a HashMap?
The following code snippet works with options filled in:

HashMap options = new HashMap         


        

Answer 1

Acording to your first code snipet seems ok, but I've got similar behavior caused by bad programing. Have you checked the "options" variable is not null before the put call?

I'm using Struts2 (2.3.3) webapp and use a HashMap for displaying results. When is executed (in a class initialized by an Action class) :

if(value != null) pdfMap.put("date",value.toString());
else pdfMap.put("date","");

Got this error:

Struts Problem Report

Struts has detected an unhandled exception:

Messages:   
File:   aoc/psisclient/samples/PDFValidation.java
Line number:    155
Stacktraces

java.lang.NullPointerException
    aoc.psisclient.samples.PDFValidation.getRevisionsDetail(PDFValidation.java:155)
    aoc.action.signature.PDFUpload.execute(PDFUpload.java:66)
    sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    ...

Seems the NullPointerException points to the put method (Line number 155), but the problem was that de Map hasn't been initialized before. It compiled ok since the variable is out of the method that set the value.