I have a Trade object in Java which has methods setTradeId() and getTradeId().

Hibernate automatically sets a value for the tradeid which is the primary key of this table.

Java Code:
-----------
Trade trade = new Trade();
//trade.setId(189); // Automatic generation.I dont need to invoke this method.
trade.setTradeDate(new Date());
trade.setName("Testing");

<class name="com.aurica.fx.options.trade.Trade" table="TRADE">

<id name="TradeId"
type="int"
column="TRADEID" >
<generator class="assigned"/>
</id>


Now,how do I retrieve this e primary key value?

After you save and commit the primary key will be in your field. Hibernate should automatically fill the field for you. You might want to just try to see if it's there after a save, because I could be wrong about the commit.