Exception in thread "main" java.lang.NullPointerException error JDeveloper 12c

Question

Hello,
I am trying to call a java stored procedure in java application. I am using ORACLE database and JDeveloper.
I am getting error "Exception in thread "main" java.lang.NullPointerException. I have no idea what have I been doing wrong.
I have a table "Beer" and I want to select all the data out with a stored procedure which I call out of Java app.
I have a java.class file Store_A.java which I have loaded into the ORACLE database with LOADJAVA :
    import java.sql.*;
    import java.io.*;
    public class Store_a {
      public static void apskatit ()
        throws SQLException
        { String sql =
          "SELECT * FROM Beer";
        try { Connection conn = DriverManager.getConnection("jdbc:default:connection:");
          PreparedStatement pstmt = conn.prepareStatement(sql);
          ResultSet rset = pstmt.executeQuery();
          rset.close();
          pstmt.close();
        catch (SQLException e) {System.err.println(e.getMessage());
Then I have created a procedure which I plan to call out in java:
    CREATE OR REPLACE PACKAGE Store_a AS
    PROCEDURE apskatit;
    END Store_a;
    CREATE OR REPLACE PACKAGE BODY Store_a AS
    PROCEDURE apskatit AS LANGUAGE JAVA
    NAME 'Store_a.apskatit()';
    END Store_a;
And I have a java file that I have created with JDeveloper 12c:
    import java.sql.Connection;
    import java.sql.DriverManager;
    import java.sql.ResultSet;
    import java.sql.SQLException;
    public class Class1 {
         * @param args
        public static void main(String[] args) throws SQLException {
            Connection conn = null;
            try {
                Class.forName("oracle.jdbc.driver.OracleDriver");
                //Izveidojam savienojumu
                conn = DriverManager.getConnection("jdbc.oracle.thin:@localhost:1521", "SYSTEM", "asdasd");
                // Izveidojam callable statement
                CallableStatement stmt = conn.prepareCall("CALL Store_a.apskatit()");
                ResultSet resul = stmt.executeQuery();
                while (resul.next()) {
                    System.out.println(resul.getInt(1) + "\t" + resul.getString(2));
            } catch (ClassNotFoundException e) {
                e.printStackTrace();
            } finally {
                try {
                    conn.close();
                } catch (SQLException e) {
                    e.printStackTrace();
When I try to run the java file, I get this error "Exception in thread "main" java.lang.NullPointerException at client.Class1.main(Class1.java:29).
So the line I get error in is "conn.close();"
How to fix this?
Thank you very much in advance.

Answer 1

I am trying to call a java stored procedure in java application. I am using ORACLE database and JDeveloper.
I am getting error "Exception in thread "main" java.lang.NullPointerException. I have no idea what have I been doing wrong.
Maybe you haven't read it yet but I told you in your other thread what you were doing wrong and, step by step, how to address the problem.
https://forums.oracle.com/thread/2611124
I'm not going to repeat everything again just this one main piece of advice:
Until you get you code working outside the database don't even bother trying to load it into the DB and create a Java stored procedure.
You are trying to deal with too many different issues at the same time. Unless you solve your primary Java problem by fixing the code outside the DB you will have nothing but problems loading it into the DB.
And just get rid of this line of code - you don't need it anymore and it hasn't been done like that for many years now:
Class.forName("oracle.jdbc.driver.OracleDriver");