CODEWITHSUNDEEP
javaexceptionpointersnull
Ragini
Ragini

Reputation: 1539

null value in if condition and null pointer exception java

I want to do something like below in java.

String subject=null,receiver=null,subject_db=null,receiver_db=null,cc=null,cc_db=null;
suject=msg.getSubject();
sub_db=rs.getString("subject");
receiver=msg.getreceiver();
receiver_db=rs.getString("receiver");
cc=msg.getcc();
cc_db=rs.getString("cc"); String foldername;

if((subject.equals(sub_db)) && (receiver.equals(receiver_db)) && (cc.equals(cc_db)))
  foldername="spam";
else
  foldername="Inbox";

As you can see here, any of the variables can be null. If this happens then it throws me NullPointerException. Is there any way I can do like, String s1=null and String s2=null and if I compare if(s1.equals(s2)) then it returns me true... I know above code is not gonna work to achieve this. But how do I do that in some other way ?

I am really sorry if I have failed to explain my problem properly...

I would appreciate any help..

Thank you..

Upvotes: 1

Views: 8338

Answers (3)

ggrigery
ggrigery

Reputation: 411

if((s1 == null && s2 == null) || s1.equals(s2))

Upvotes: 3

raveturned
raveturned

Reputation: 2677

How about something like…

private boolean nullsOrEquals(string s1, string s2)
{
  if (s1 == null)
    return (s2 == null);

  return s1.equals(s2);
}

if (nullsOrEquals(subject, sub_db) && [etc])
  foldername="spam";
else
  foldername="Inbox";

Upvotes: 4

STM
STM

Reputation: 964

If I understand you want to compare Strings even if they are null.

For that just add a condition in the if statement like:

if((string1 == null && string2==null) || string1.equals(s2))
{
//Your code
}

Upvotes: 1

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