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POmysql and java jdbc call from another class [runtime application]
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copied!<p><strong>the problem is due to the **app.java **being called in response to a plugin start i.e in run time environment. i tried addinG "mysql-connector-java-5.1.18-bin" in the runtime-EclipseApplication too but it does NOT work still.</strong> </p> <p>my mysql / java connection works perfectly when stand alone but i can not develope a connection and get an exception when the connection is called from another class.</p> <p>i have made a <strong>class DataAccessHelper.java</strong></p> <pre><code> package dataBase; import java.sql.Connection; import java.sql.DriverManager; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.SQLException; import java.sql.Statement; import java.util.Date; public class DataAccessHelper { private Connection connect = null; private Statement statement = null; private PreparedStatement preparedStatement = null; private ResultSet resultSet = null; public void readDataBase() throws Exception { try { // This will load the MySQL driver, each DB has its own driver Class.forName("com.mysql.jdbc.Driver"); // Setup the connection with the DB connect = DriverManager .getConnection("jdbc:mysql://localhost/feedback?" + "user=sqluser&password=sqluserpw"); // Statements allow to issue SQL queries to the database statement = connect.createStatement(); // Result set get the result of the SQL query resultSet = statement .executeQuery("select * from FEEDBACK.COMMENTS"); writeResultSet(resultSet); // PreparedStatements can use variables and are more efficient preparedStatement = connect .prepareStatement("insert into FEEDBACK.COMMENTS values (default, ?, ?, ?, ? , ?, ?)"); // "myuser, webpage, datum, summery, COMMENTS from FEEDBACK.COMMENTS"); // Parameters start with 1 preparedStatement.setString(1, "Test"); preparedStatement.setString(2, "TestEmail"); preparedStatement.setString(3, "TestWebpage"); preparedStatement.setDate(4, new java.sql.Date(2009, 12, 11)); preparedStatement.setString(5, "TestSummary"); preparedStatement.setString(6, "TestComment"); preparedStatement.executeUpdate(); preparedStatement = connect .prepareStatement("SELECT myuser, webpage, datum, summery, COMMENTS from FEEDBACK.COMMENTS"); resultSet = preparedStatement.executeQuery(); writeResultSet(resultSet); // Remove again the insert comment preparedStatement = connect .prepareStatement("delete from FEEDBACK.COMMENTS where myuser= ? ; "); preparedStatement.setString(1, "Test"); preparedStatement.executeUpdate(); resultSet = statement .executeQuery("select * from FEEDBACK.COMMENTS"); writeMetaData(resultSet); } catch (Exception e) { throw e; } finally { close(); } } private void writeMetaData(ResultSet resultSet) throws SQLException { // Now get some metadata from the database // Result set get the result of the SQL query System.out.println("The columns in the table are: "); System.out.println("Table: " + resultSet.getMetaData().getTableName(1)); for (int i = 1; i<= resultSet.getMetaData().getColumnCount(); i++){ System.out.println("Column " +i + " "+ resultSet.getMetaData().getColumnName(i)); } } private void writeResultSet(ResultSet resultSet) throws SQLException { // ResultSet is initially before the first data set while (resultSet.next()) { // It is possible to get the columns via name // also possible to get the columns via the column number // which starts at 1 // e.g. resultSet.getSTring(2); String user = resultSet.getString("myuser"); String website = resultSet.getString("webpage"); String summery = resultSet.getString("summery"); Date date = resultSet.getDate("datum"); String comment = resultSet.getString("comments"); System.out.println("User: " + user); System.out.println("Website: " + website); System.out.println("Summery: " + summery); System.out.println("Date: " + date); System.out.println("Comment: " + comment); } } // You need to close the resultSet private void close() { try { if (resultSet != null) { resultSet.close(); } if (statement != null) { statement.close(); } if (connect != null) { connect.close(); } } catch (Exception e) { } } } </code></pre> <p>when i run this class directly from <strong>main.java</strong></p> <pre><code> package dataBase; public class main { public static void main(String[] args) throws Exception { DataAccessHelper dao = new DataAccessHelper(); dao.readDataBase(); } } </code></pre> <p>it runs perfectly. however, when i try to call in my other class <strong>App.java</strong></p> <pre><code> package newmodulewizrd.ui; import java.awt.Dimension; import java.awt.FlowLayout; import java.sql.SQLException; import javax.swing.JFrame; import org.eclipse.jdt.core.JavaModelException; import dataBase.DataAccessHelper; public class App extends JFrame { ScreenContainer screen; public App(boolean flag) { } public App() throws JavaModelException, ClassNotFoundException, SQLException{ FlowLayout fl=new FlowLayout(); this.setLayout(fl); screen = new ScreenContainer(); DataAccessHelper con= new DataAccessHelper(); try { con.readDataBase(); } catch (Exception e) { e.printStackTrace(); } newModuleWizard.bl.Module module = new newModuleWizard.bl.Module(); screen.addScreen(new Module(module,con),"module");// Screen1 screen.addScreen(new Description(module,con),"description"); screen.addScreen(new PPT(module,con), "ppt"); screen.addScreen(new Role(module,con), "role"); screen.addScreen(new MI(module,con), "MI"); this.add(screen); this.add(new Controls(screen)); this.setSize(new Dimension(800,600)); } public static void main(String[] args) throws JavaModelException, ClassNotFoundException, SQLException { new App().setVisible(true); } } </code></pre> <p>it gives an <strong>exception</strong></p> <pre><code> java.lang.ClassNotFoundException: com.mysql.jdbc.Driver </code></pre> <p>apparently my problem is the same as </p> <p><a href="https://stackoverflow.com/questions/2888485/java-mysql-how-to-access-connection-from-another-class">Java / MySQL - How to access connection from another class?</a> </p> <p>however, i can not benefit from it cuz the solution provided is according to the code provided which is somehow not accessible to be [most probably the link died]</p> <p><strong>so plz help anyone</strong></p>

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