Postgresql JDBC process consumes more memory than psql client

  We run same update or delete SQL statement “ DELETE FROM … WHERE … “  the table is a hash partition table (256 hash partitions). When run the sql from Postgresql JDBC driver, it soon increased to 150MB memory (RES filed from top command),       but when run the same SQL from psql , it only consumes about 10MB memory.  UPDATE statements is similar , need 100MB memory, even it delete or update 0 rows.  Any specific control about Postgresql JDBC driver ?

Thanks,

James