错误：线程“ AWT-EventQueue-0”中的异常java.lang.ClassCastException：

Question

My code is :

try {
    Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver");
    String connectionUrl = "jdbc:sqlserver://localhost:1433;" +
    "databaseName=Java-Test;user=sa;password=199088037635;";
    link = (Connection) DriverManager.getConnection(connectionUrl);

} catch (ClassNotFoundException e) {
    System.out.println("Class Error: "+ e.toString());
} catch (SQLException se) {
    System.out.println("Driver Error: " + se.toString());
}

I get the error :

Exception in thread "AWT-EventQueue-0" java.lang.ClassCastException: com.microsoft.sqlserver.jdbc.SQLServerConnection cannot be cast to com.sun.corba.se.pept.transport.Connection at SQL.createAndShowGUI(SQL.java:42)

Similar code in other projects runs correctly. But in this project it doesn't run.

Answer 1

Check your imports. When you type in a class name the IDE checks whether it's something already in scope, and, if not, it gives you suggestions for what you can import. The problem is, the IDE doesn't know which suggestions are more relevant so it can't order them so the most likely one comes up first. Nevertheless, people get used to taking the IDE's first suggestion reflexively, which can result in getting something (with the same name but from a totally different package) that isn't what you want at all.

I'm guessing the IDE inserted a line like

import com.sun.corba.se.pept.transport.Connection;

where it should be

import java.sql.Connection;

which is the JDBC interface that com.microsoft.sqlserver.jdbc.SQLServerConnection implements.

DriverManager.getConnection returns a java.sql.Connection and usually that interface exposes all the funcitonality you need, so you shouldn't need a cast here.

Answer 2

Include this library in the build path of your project.

In Eclipse, this is done by **right clicking on the project > properties > Java Build Path > Add JARs...