Null Pointer Exception

[Krishna Kodali]

This program compiled but i am getting runtime null pointer exception.

Please let me know if i am doing any thing wrong.

import java.sql.*;
import javax.sql.*;
import java.util.Properties;
public class JDBCExample { 
public static void main(String[] args) throws SQLException,InstantiationException,ClassNotFoundException,IllegalAccessException{
Connection conn = null;
Statement stmt = null;
String query = "select * from derbyDB;";
Properties props= new Properties();
props.put("user","user1");
props.put("password","user1");
try{
Class.forName("org.apache.derby.jdbc.EmbeddedDriver").newInstance();
conn = DriverManager.getConnection("jdbc:derby:MyDbTest",props);
if(conn != null){
System.out.println("Connected to MyDbTest database");
}
stmt = conn.createStatement();
ResultSet rs = stmt.executeQuery(query);
while (rs.next()){
int year = rs.getInt("num");
String address = rs.getString("addr");
System.out.println(year+"\t"+address);
}
}
catch (SQLException e){
e.printStackTrace();
}
finally{
stmt.close();
}
}
}

Output:
Exception in thread "main" java.lang.NullPointerException
at JDBCExample.main(JDBCExample.java:30)

[Bear Bibeault]

Hmmm, I'm trying to look at your code, but the stubborn forum software has made it look all wonky. If you use CODE tags when posting code to the forums (see the FAQ at ⇒ UseCodeTags ⇐) they tell it "Hey! Keep your hands off my formatting!" and your code will look just like when you cut and pasted it into the reply. Cool, no?

[Christophe Verré]

The error message tells you that the NullPointerException happens at line 30. Which line is this referring to ?

Also, although you check if "conn" is not null, you don't do anything in case "conn" is null.