JsonMappingException even if checking for null values

Question

I am getting an exception when doing a null and empty check for a string that I am passing to an ObjectMapper Json Parser method. This is my code here:

private static final ObjectMapper OBJECT_MAPPER = new ObjectMapper();

@RequestMapping(value = "/url", method = RequestMethod.GET)
    public ModelAndView displayStuff(
            @RequestParam(value = "item") int itemCode) throws JsonProcessingException, IOException {


           if (!text.equals("") || text != null) {
                JsonNode jsonThresholds = OBJECT_MAPPER.readTree(text);
                do stuff()..

          }else {
               do nothing();
          }
     }

I am getting this exception:

com.fasterxml.jackson.databind.JsonMappingException: No content to map due to end-of-input
 at [Source: java.io.StringReader@182d2fd7; line: 1, column: 1]
    at com.fasterxml.jackson.databind.JsonMappingException.from(JsonMappingException.java:164)
    at com.fasterxml.jackson.databind.ObjectMapper._initForReading(ObjectMapper.java:2840)
    at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:2782)
    at com.fasterxml.jackson.databind.ObjectMapper.readTree(ObjectMapper.java:1659)

Could someone please explain to me what is happening and how I can fix this.

Thankyou

change it to !text.equals("") && text != null that may work.. — Kishan Bheemajiyani
– Kishan Bheemajiyani, Commented Oct 21, 2014 at 5:57

Madhawa Priyashantha · Accepted Answer · 2014-10-21 06:21:45Z

2

change

!text.equals("") || text != null

to

text != null && !text.equals("")

because even text="" then text != null become true and goes to inside of if..

you should first check null or not because if value is null .equls will give nullpointer exception

this is wrong too

 !text.equals("")  &&  text != null 
       ↑
     null pointer Exception can be occurred here

edited Oct 21, 2014 at 6:21

answered Oct 21, 2014 at 5:55

Madhawa Priyashantha

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7 Comments

DnR Over a year ago

perhaps text.trim().equals(""), to get rid of the empty space

Lilu Patel Over a year ago

Thank you, it works for empty strings but if there is no string, I still get a null pointer exception. Why would this be?

Kishan Bheemajiyani Over a year ago

obj.toString().equals("{}"); this could be what u looking for in that case.

Baby Over a year ago

@LiluPatel OBJECT_MAPPER is null then

Madhawa Priyashantha Over a year ago

@LiluPatel check my updated answer .actually you should swap null check and empty check.first you should check null or not

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