Java MYSQL Nullpointerexception

Question

Hey guys i'm trying to connect to my database and run a query. it all works apart from the query execution (after narrowing it down i found it to be this) Below i my code:

              Statement statement = null;
          ResultSet result;

           result = statement.executeQuery(query);//this is where error is being caused

           while(result.next())
           {
               Print("ID: " + result.getString("id"));
               Print("USER: " + result.getString("username"));
               Print("PASS: " + result.getString("password"));
           }

I get this returned:

database!java.lang.NullPointerException

Thanks for any help you give me

This is where I started with Java - download.oracle.com/javase/tutorial/java/index.html — RHT
– RHT, Commented Oct 13, 2011 at 1:34

Icarus · Accepted Answer · 2011-10-13 00:30:27Z

3

The query looks right. Surely the statement variable is NULL and you are trying to call executeQuery.

UPDATE:

Try this:

Statement statement = conn.createStatement ();

where conn is a Connection object. I'm sure you have one of those objects somewhere in your code.

edited Oct 13, 2011 at 0:30

answered Oct 13, 2011 at 0:22

Icarus

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4 Comments

Icarus Over a year ago

You updated your question after I posted my answer. I'm glad I guessed. doing statement =null; and right after statement.executeQuery(); is obvious that will throw a nullpointerexception.

Icarus Over a year ago

No, the opposite: It will never work! You are setting statement to NULL! You have to create an instance of statement before you can call any methods.

Duncan Palmer Over a year ago

@Icarus how would i get it to work then? If i don't it throws an error saying I need to Initialize the variable.

fireshadow52 Over a year ago

@DuncanPalmer Set the statement variable to something other than null.

Duncan Palmer · Accepted Answer · 2011-10-13 00:32:06Z

0

Fixed my problem by using a prepared statement:

           String query = "SELECT * FROM users";

          PreparedStatement statement = null;
          ResultSet result;
          statement  = conn.prepareStatement(query);
          result = statement.executeQuery(query);

           while(result.next())
           {
               Print("ID: " + result.getString("id"));
               Print("USER: " + result.getString("username"));
               Print("PASS: " + result.getString("password"));
           }

Thanks for your help

answered Oct 13, 2011 at 0:32

Duncan Palmer

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1 Comment

Boann Over a year ago

You're specifying the query twice so the preparedness of it isn't used. result=statement.executeQuery() will do.

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