User should modify their application to prepare once and execute n times.
ps2 = this.conn.prepareStatement("insert into TESTDB values(?, ?, ?);");
for(int i=0; i<list.size();i++)
tData = (TestData)list.get(i);
To improve performance, we suggest writing application as the above example i.e. PREPARES SQL statement just once and then EXECUTE it as many times as they need during the run of the program.