java.lang.NullPointerException** error?

Question

I am trying to add records to Sql Server in Java. In this function, program gives an error like that:

Connected
1
2
Error java.lang.NullPointerException

It is the output..

Function is below:

public class DB {

    Connection con = null;
    Statement stmt Nnull ;
    component cmp = new Component();

    public long pSave(Component cmp) {
        String i = cmp.getI();
        String s = cmp.getS();
        String a = cmp.getA();
        int t = cmp.getT();
        int c = cmp.getC();

        System.out.println("1");

        try {
            System.out.println("2");
            stmt = con.createStatement();

            System.out.println("3");
            String SQL =
                "INSERT INTO kisi (cl1,cl2,cl3,cl4,cl5) "
                + "VALUES(" + i + "," + s + "," + a + "," + c + "," + t + ")";

            System.out.println("4");
            stmt.executeUpdate(SQL);

            System.out.println("Success");

            return 1;
        } catch(Exception e) {
            System.out.println("Error " + e);
            return 0;
        }
    }

}

You didnt initialize the connection ('con') which you are calling when you're trying to initialize the statement.. ('stmt = con.createstatement') — Rob
– Rob, Commented Nov 3, 2011 at 13:09
Full stack trace please? Don't just print the Exception message, you're hiding what is really going on. At lest for this purpose, use e.printStackTrace() — pcalcao
– pcalcao, Commented Nov 3, 2011 at 13:10

AlexR · Accepted Answer · 2011-11-03 13:12:36Z

4

Connection con = null;
......
stmt = con.createStatement();
        ^

The connection is not initialized. You have to connect to DB in order to retrieve data.

answered Nov 3, 2011 at 13:12

AlexR

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Comments

Oleg Mikheev · Accepted Answer · 2011-11-03 13:13:24Z

4

NullPointerException means that you're trying to call a method on a null object. That null object is your con that you never initialize. You should add these two lines to initialize it:

Driver d = (Driver)Class.forName("com.microsoft.jdbc.sqlserver.SQLServerDriver").newInstance();
con = DriverManager.getConnection("jdbc:microsoft:sqlserver://server:1433", "userName", "password");

answered Nov 3, 2011 at 13:13

Oleg Mikheev

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Mechkov · Accepted Answer · 2011-11-03 13:11:07Z

2

You need to create a Connection object first. You have: Connection con = null;

So, you cant create a statement from a connection that is null.

answered Nov 3, 2011 at 13:11

Mechkov

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Rob · Accepted Answer · 2011-11-03 13:11:08Z

2

You didnt initialize the connection con which you are calling when you're trying to initialize the statement.. stmt = con.createstatement

answered Nov 3, 2011 at 13:11

Rob

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Comments

nicholas.hauschild · Accepted Answer · 2011-11-03 13:25:29Z

0

A little bit of debugging may help.

You may notice your output says Connected 1 2 Error java.lang.NullPointerException. The 1 and 2 suggest that you reached the first and second println statements and the Error NPE suggests that a line of code after those failed. The third println is never hit, which means your NPE happened between 2 and 3. There exists a single statement between these two, and that is where you are getting your NPE.

So the question now is, what could be causing the NPE? I will leave that as an exercise for the reader. :)

edited Nov 3, 2011 at 13:25

answered Nov 3, 2011 at 13:12

nicholas.hauschild

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