1. Common Pitfalls

2. 1. Not specifying columns in your select statement
(select *)

3. .
.
StringBuffer queryString = new StringBuffer();
queryString.append("SELECT DISTINCT o.name, o.code, o.price, d.discount “);
queryString.append("FROM com.exist.model.Order as o, “);
queryString.append("com.exist.model.Discounts as d “);
.
.
.
Session session = sessionFactory.getCurrentSession();
Query selectQuery = session.createQuery(queryString.toString());
List<Order> orders= selectQuery.list();
.
.
.
List<OrderTo> orderTo = new ArrayList<OrderTo>();
...
for(Order order:orders){
OrderTo oto = new OrderTo
oto.setName(order.getName());
.
.
.
orderTo.add(oto);
}
.
.
.
2. Select and Transfer

4. .
.
.
StringBuffer queryString = new StringBuffer();
queryString.append("SELECT DISTINCT new com.exist.to.OrdersTO ");
queryString.append("(o.name, o.code, o.price, d.discount) ");
queryString.append("FROM com.exist.model.Orders as o, ");
queryString.append("com.exist.model.Discounts as d “);
.
.
.
Session session = sessionFactory.getCurrentSession();
Query selectQuery = session.createQuery(queryString.toString());
.
.
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List<OrdersTO> data = selectQuery.list();

5. 3. Not delegating computations
.
.
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double bills = someService.getBills(referenceNo);
double payments = someService.getPayments(referenceNo)
double due = bills - payments;
.
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.

6. public class Computations {
private SomeService someService;
private double bills;
private double payments;
private double due;
public Computations(SomeService someService, String reference) {
bills = someService.getBills(referenceNo);
payments = someService.getPayments(referenceNo)
due = bills - payments;
}
... <getters of bills, payments and due>
}

7. .
.
.
Computations computations = new Computations(someService, referenceNo);
double bills = computations.getBills();
double payments = computations.getPayments();
double due = computations.getDue();
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.

8. 4. equals String literal
variable.equals(“String Literal”);

9. “String literal”.equals(variable);

10. 5. Computing using double or
Double
double minuend = 1.1d;
double subtrahend = 1.0d;
double difference = minuend – subtrahend;
Or
Double minuend = 1.1d;
Double subtrahend = 1.0d;
Double difference = minuend.doubleValue() – subtrahend.doubleValue();

11. BigDecimal minuend = new BigDecimal(1.1).setScale(2, RoundingMode.HALF_EVEN);
BigDecimal subtrahend = 1.0d;
BigDecimal difference = minuend.subtract(subtrahend);

12. 6. using objects in if
If (object.getBooleanProperty()) {
...
}

13. if (object!=null && object.getBooleanProperty()) {
...
}
Or
if (object!=null && object.getNumericProperty()>0) {
...
}

14. Thanks!