Обсуждение: Unable to compile java file with all Classpaths set
I'm in a bit of a dilemma. I need to connect to a PostgreSQL database through JAVA and so naturally I checked out the JDBC drivers. I downloaded the JDBC 3 driver (both 8.2 and the 8.3dev) as I am using JDK 1.5. I set the CLASSPATH in the environment variables to C:\postgresql.jar (I renamed the one i was using to this). I then wrote a test file that will make sure that I've set up everything correctly. I found this sample on the net so I decided to use it... I only wanted it to compile, nothing more.
import java.sql.*;
public class maxi{
public static void main(String[] args){
Class.forName("org.postgresql.Driver");
String url = "jdbc:postgresql://server8.cs.uofs.edu/";
String dbname = "uofsis";
String usernm = "bi";
String passwd = "";
Connection db = DriverManager.getConnection(url+dbname, usernm, passwd);
Statement st = db.createStatement();
String sql = "SELECT name, title " + "FROM faculty f, course c " + "WHERE f.id = c.instructor";
ResultSet rs = st.executeQuery(sql);
st.close();
db.close();
}
}
Every time I compile it I get the following output:
C:\>javac maxi.java
maxi.java:5: unreported exception java.lang.ClassNotFoundException; must be caug
ht or declared to be thrown
Class.forName("org.postgresql.Driver");
^
maxi.java:11: unreported exception java.sql.SQLException; must be caught or decl
ared to be thrown
Connection db = DriverManager.getConnection (url+dbname, usernm, pass
wd);
^
maxi.java:13: unreported exception java.sql.SQLException; must be caught or decl
ared to be thrown
Statement st = db.createStatement();
^
maxi.java:16: unreported exception java.sql.SQLException; must be caught or decl
ared to be thrown
ResultSet rs = st.executeQuery(sql);
^
maxi.java:18: unreported exception java.sql.SQLException; must be caught or decl
ared to be thrown
st.close();
^
maxi.java:19: unreported exception java.sql.SQLException; must be caught or decl
ared to be thrown
db.close();
^
6 errors
I've tried versions 1.5 and 1.6 of the JDK on Windows XP, Windows Vista, and Ubuntu Linux using JDBC 3 and JDBC 4 drivers for 8.0, 8.2, and 8.3dev and they all output the same errors. I also tried writing it using NetBeans and importing the jar file into its libraries for the test project I created. The same errors appeared. What am I missing here?? Perhaps somebody can help.
Thanks
Kareem
import java.sql.*;
public class maxi{
public static void main(String[] args){
Class.forName("org.postgresql.Driver");
String url = "jdbc:postgresql://server8.cs.uofs.edu/";
String dbname = "uofsis";
String usernm = "bi";
String passwd = "";
Connection db = DriverManager.getConnection(url+dbname, usernm, passwd);
Statement st = db.createStatement();
String sql = "SELECT name, title " + "FROM faculty f, course c " + "WHERE f.id = c.instructor";
ResultSet rs = st.executeQuery(sql);
st.close();
db.close();
}
}
Every time I compile it I get the following output:
C:\>javac maxi.java
maxi.java:5: unreported exception java.lang.ClassNotFoundException; must be caug
ht or declared to be thrown
Class.forName("org.postgresql.Driver");
^
maxi.java:11: unreported exception java.sql.SQLException; must be caught or decl
ared to be thrown
Connection db = DriverManager.getConnection (url+dbname, usernm, pass
wd);
^
maxi.java:13: unreported exception java.sql.SQLException; must be caught or decl
ared to be thrown
Statement st = db.createStatement();
^
maxi.java:16: unreported exception java.sql.SQLException; must be caught or decl
ared to be thrown
ResultSet rs = st.executeQuery(sql);
^
maxi.java:18: unreported exception java.sql.SQLException; must be caught or decl
ared to be thrown
st.close();
^
maxi.java:19: unreported exception java.sql.SQLException; must be caught or decl
ared to be thrown
db.close();
^
6 errors
I've tried versions 1.5 and 1.6 of the JDK on Windows XP, Windows Vista, and Ubuntu Linux using JDBC 3 and JDBC 4 drivers for 8.0, 8.2, and 8.3dev and they all output the same errors. I also tried writing it using NetBeans and importing the jar file into its libraries for the test project I created. The same errors appeared. What am I missing here?? Perhaps somebody can help.
Thanks
Kareem
Kareem Habib wrote:
> Every time I compile it I get the following output:
>
> C:\>javac maxi.java
> maxi.java:5: unreported exception java.lang.ClassNotFoundException; must be
> caug
> ht or declared to be thrown
> Class.forName("org.postgresql.Driver");
> ... ^
Please read
http://java.sun.com/docs/books/tutorial/essential/exceptions/
--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com
Kareem,
The errors are telling you exactly what is wrong. Your “sample” from the net is bad. There are method calls in the code sample you posted that throw checked exceptions. You either need to wrap these in a try/catch block and explicitly catch them, or specify that your main() method throws them.
If you just want to get it working, change your main() declaration line to:
public static void main(String[] args) throws Exception {
-- Jeff
The errors are telling you exactly what is wrong. Your “sample” from the net is bad. There are method calls in the code sample you posted that throw checked exceptions. You either need to wrap these in a try/catch block and explicitly catch them, or specify that your main() method throws them.
If you just want to get it working, change your main() declaration line to:
public static void main(String[] args) throws Exception {
-- Jeff