Give me a hand

I have installed jdk1.4.
My java program which use postgresql7.1.3 often give me the 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 jdbc driver I use is pgjdbc2.jar.
The classpath I set is:
CLASSPATH=/usr/java/jdk/lib:/usr/java/jdk/jre/lib:/usr/java/jdk/lib/tools.jar:/usr/share/pgsql/pgjdbc2.jar:/home/sjf:/home/sjf/ant/lib/ant.jar:/home/sjf/ant/lib/xerces.jar

I also try jdk 1.3 and jdbc7.1_1.2,the error is the same.
What wrong with this?
Is it the postgresql installing problem?
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