bothering error

I download a small java program which use jdbc to connect to postgresql.But I meet a error like this:
java.lang.NoSuchMethodError: java/sql/Statement.getResultSetConcurrency()I
at org.postgresql.jdbc2.Connection.getResultSet(Connection.java:216)
at org.postgresql.core.QueryExecutor.execute(QueryExecutor.java:121)
at org.postgresql.Connection.ExecSQL(Connection.java:398)
at org.postgresql.jdbc2.Statement.execute(Statement.java:130)
at HelloPostgresql.<init>(HelloPostgresql.java:30)
at HelloPostgresql.main(HelloPostgresql.java:92)

The jdk I use is j2sdk1.4.0_01
The jdbc driver I use is pgjdbc2.jar which I downloaded from http://jdbc.postgresql.org/download.html.
What is the problem? give me some suggestion
thanks

jack
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