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null pointer exceptiion

jyotsana dang
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Joined: Sep 26, 2003
Posts: 135
what is null pointer exception ? And how do we rectify it? I have written a JSP code for inserting values to a database. But Iam getting a null pointer exception for the same..
Natraj Gudla
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Joined: Feb 09, 2003
Posts: 34
When ever a "null" is used when an object is required, a NullPointerException is thrown.
To avoid this we need to be careful while assiging object references and creating structures.Explicit check on the null references before they are used can avoid such exceptions.
Natraj Gudla
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Joined: Feb 09, 2003
Posts: 34
sorry..a correction...it is a null not a string "null".
Praful Thakare
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Joined: Feb 10, 2001
Posts: 627
Jyotsana ,
NullPointerEception is thrown whenever you use dot(.) with and variable which is object and contains null value.
say you have String s=null;
and you say s.substring(); this is same as null.substring(); which throws an nullpointer exception.
In your case I guess you are getting null pointer exception during creating connection.
just chek if your connection object is not null before createing statment like..stmt=con.createStatement();
Cheers
Praful


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Bear Bibeault
Author and ninkuma
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Joined: Jan 10, 2002
Posts: 61071
    
  66

Not a JSP concept. Moving this to the Java in General(beginner) forum.
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subject: null pointer exceptiion