Home / Questions

All Questions

Martin Hope
x3k
Asked: 2020-12-17 04:05:51 +0800 CST
  • 16

When checking if my list that is returned from a DB query contains a number with .contains()it returns false.

Return false:

System.out.println(listaBd);      // Output:[1, 2]
listaBd.contains(Long.valueOf(1)) // False

The problem does not seem from the code but from the list, since if I create the list by hand it returns true.

List <Long> listaLong = new ArrayList();
listaLong.add(1L);
listaLong.add(2L);
System.out.println(listaLong);      // Output:[1, 2]
listaLong.contains(Long.valueOf(1)) // True

I get the list as follows:

List<Long> results = new ArrayList<Long>();
results = (List<Long>)QueryUtil.list(query, getDialect(), -1, -1); //Liferay

And from what I understand, if it does not give any exceptionwhen casting it, it is because they are Longsvalid

The queryis something like this very simplified (with lots of joins and wheres that I'm going to exclude):

select idIdioma
from mitable;

idIdiomais one fkof a kindNUMBER(10,0)

java
Martin Hope
César
Asked: 2020-12-05 07:13:57 +0800 CST
  • 17

Grace Hopper 's famous quote :

It is easier to ask for forgiveness than to ask for permission.

Which is popular within the programming community, makes me wonder if this applies to Python code, I often feel inclined (for ease) to use exceptions. Consider the following case:

lista = []

# Pedir perdón
try:
    elemento = lista[0]
except IndexError:
    elemento = None

# Pedir permiso
elemento = None
if len(lista) > 1:
    elemento = lista[0]

In summary what I want to know is, is there any performance difference in Python when using one or the other?

I ask this because I have heard from a friend that in Java, for example, it is expensive to use the block try {} catch {}due to a series of processes carried out to fill the stack trace which makes you think carefully before using them. Does the same happen for Python?

python
Martin Hope
Marcos Crispino
Asked: 2020-12-03 11:30:49 +0800 CST
  • 17

Using the new Contacts Framework in iOS 9, how can I get the contact creation date?

In previous versions, using the Address Book Framework, you could do:

ABRecordRef person = ...
NSDate *creationDate = (__bridge_transfer NSDate *)ABRecordCopyValue(person, kABPersonCreationDateProperty);

but using the new framework I didn't find any property on CNContactnor any "key" to be able to get this value.

ios
Prev
Next