Solved

how to validate null value

Posted on 2012-03-16
11
205 Views
Last Modified: 2012-03-16
im retrieving a ABC object from database. the properties of object ccid is null and the achflag is N. ccid is integer and achflag is varchar(1)
log.debug values:
ccid null
achflag N

in my if condition it throws a null pointer exception.
if(ABC.getccid() == null && ABC.getachflag() == "N"){
//do something
}

my if condition fails and does not go in if loop
0
Comment
Question by:Newton21205
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 8
  • 3
11 Comments
 
LVL 47

Expert Comment

by:for_yan
ID: 37731842
if you are talking about Java (not JavaScript) then

this
if(ABC.getccid() == null && ABC.getachflag() == "N")

witll throw nullpointer because  object ABC  is null
0
 
LVL 47

Expert Comment

by:for_yan
ID: 37731846
this will not thow exception:
if(ABC != null && ABC.getccid() == null && ABC.getachflag() == "N"){
//do something
}
0
 
LVL 47

Expert Comment

by:for_yan
ID: 37731851
this will not thow exception, and this is better because if you want
to compare Strings you need to use equals() method not ==
if(ABC != null && ABC.getccid() == null && ABC.getachflag().equals("N")){
//do something
}
0
Online Training Solution

Drastically shorten your training time with WalkMe's advanced online training solution that Guides your trainees to action. Forget about retraining and skyrocket knowledge retention rates.

 

Author Comment

by:Newton21205
ID: 37731872
im checking the object is not null and is not empty as shown in log.debug values.
im doing this:
if(ABC != null){
if(ABC.getccid() == null && ABC.getachflag() == "N"){
//do something
}
}

but it throws a null pointer exception
0
 
LVL 47

Expert Comment

by:for_yan
ID: 37731875
which line exactly throws null pointer?
did you print stack trace and determine exact line?
0
 
LVL 47

Accepted Solution

by:
for_yan earned 100 total points
ID: 37731880
null pointer is thrown when you invoke method on the object which is null

this code
if(ABC != null){
if(ABC.getccid() == null && ABC.getachflag() == "N"){
//do something
}
}
should not thrwo null pointer, because you are checking upfront
check exact line using stack trace
0
 
LVL 47

Expert Comment

by:for_yan
ID: 37731882
>and achflag is varchar(1)

varchar is not Java type it is database type

what Java type is retruened by ABC.getachflag() ?

post the contents of the class ABC
0
 

Author Comment

by:Newton21205
ID: 37731903
yes i did a try catch around the if it points to the if condition.
0
 

Author Comment

by:Newton21205
ID: 37731904
the Java datatype for achflag is String varchar is the database datatype
0
 
LVL 47

Expert Comment

by:for_yan
ID: 37731905
post the code for class to which variable ABC belongs
0
 
LVL 47

Expert Comment

by:for_yan
ID: 37731906
what code is in the part //do something ?
0

Featured Post

Instantly Create Instructional Tutorials

Contextual Guidance at the moment of need helps your employees adopt to new software or processes instantly. Boost knowledge retention and employee engagement step-by-step with one easy solution.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Title # Comments Views Activity
maximize the sum of fractions 33 74
Javascript: Range object 16 33
Set css in function 11 54
Make icons act like add/minus for qtys 6 43
Go is an acronym of golang, is a programming language developed Google in 2007. Go is a new language that is mostly in the C family, with significant input from Pascal/Modula/Oberon family. Hence Go arisen as low-level language with fast compilation…
In this post we will learn how to connect and configure Android Device (Smartphone etc.) with Android Studio. After that we will run a simple Hello World Program.
Video by: Michael
Viewers learn about how to reduce the potential repetitiveness of coding in main by developing methods to perform specific tasks for their program. Additionally, objects are introduced for the purpose of learning how to call methods in Java. Define …
Viewers will learn about basic arrays, how to declare them, and how to use them. Introduction and definition: Declare an array and cover the syntax of declaring them: Initialize every index in the created array: Example/Features of a basic arr…
Suggested Courses

732 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question