java.lang.ClassCastException: com.mchange.v2.c3p0.impl.NewProxyConnection

Question

i am getting the following

java.lang.ClassCastException: com.mchange.v2.c3p0.impl.NewProxyConnection

when the following code executes. could you please help me how to solve.

            ComboPooledDataSource connPool = new ComboPooledDataSource();
        connPool .setJdbcUrl(PropertyReader.getSystemProperty(DB_URL));         
        connPool .setUser(PropertyReader.getSystemProperty(DB_USER));           
        connPool .setPassword(Decryption.getDecryptedPwd(DB_PASSWORD));
        connPool .setMaxPoolSize(MAX_POOL_SIZE);
        connPool .setMaxIdleTime(MAX_IDLE_TIME);
        connPool .setMinPoolSize(MIN_POOL_SIZE);
        connPool .setMaxAdministrativeTaskTime(15);

        java.sql.Connection conn = connPool.getConnection();
        oracle.sql.CLOB c = CLOB.createTemporary(conn, false, CLOB.DURATION_SESSION);
        Writer writer = c.setCharacterStream(0L);
        writer.write(String.valueOf(pNoListDelimited).toCharArray());
                  writer.flush();
                    writer.close();

Exception stack trace

            java.lang.ClassCastException: com.mchange.v2.c3p0.impl.NewProxyConnection
            at oracle.sql.CLOB.createTemporary(CLOB.java:676)
            at oracle.sql.CLOB.createTemporary(CLOB.java:640)
            ……
            …..
            at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:269)
            at java.util.concurrent.FutureTask.run(FutureTask.java:123)
            at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:651)
            at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:676)
            at java.lang.Thread.run(Thread.java:595)

Answer 1

you are using Oracle-specific API that expects your Connection to be a particular Oracle Connection class. But the Connection you are working with is a c3p0 proxy Connection, not that Oracle Connection class.

if you want to use the Oracle-specific api, you have a few choices:

1. you can use c3p0's raw Connection operations, see http://www.mchange.com/projects/c3p0/index.html#raw_connection_ops for the precise example you are looking for;
2. c3p0 actually ships with a jar file for Oracle that performs this operation. it's rarely used and ages old, though, so a grain of salt;
3. you can upgrade to a prerelease version of c3p0-0.9.5, which supports the full JDBC4 api, and use the unwrap operation to extract the raw Oracle Connection.

good luck!