public Connection xconecta(){

try {
     Class.forName("oracle.jdbc.driver.OracleDriver");
    con=DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:XE","SYSTEM","12marzo1996");

        if (con!=null)
        {
            System.err.println("CONECTADO");
        }
        else
        {
            System.err.println("Error");
        }
    return con;
} catch (ClassNotFoundException | SQLException e) {
    System.err.println(e.getMessage());
    return null;
}
}

public void INGRESAR(){
        try {
          pst=con.xconecta().prepareStatement("insert into EJEMPLO
          values(?,?,?)");
          pst.setInt(1, 1);
          pst.setString(2, "Jose");
          pst.setString(3, "Castillo");
          pst.execute();
            } catch (SQLException e)
            {
             System.out.println(e.getMessage());
             }

         }