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首次打开app时，提示打开蓝牙权限，打开后点击开始搜索，设备列表没有显示...
本帖最后由 fun_hcf 于 2025-08-11 09:48 编辑
首次打开app时，提示打开蓝牙权限，打开后点击开始搜索，设备列表没有显示蓝牙设备，而且app卡住了点不动，后面需要先在手机系统设置先打开蓝牙，然后启动app才能搜索到设备，请...
Convert Rows to columns using 'Pivot' in SQL Server
..., 212),
(105, 2, 78),
(109, 2, 97),
(105, 3, 60),
(102, 3, 123),
(101, 3, 220),
(109, 3, 87);
If your values are known, then you will hard-code the query:
select *
from
(
select store, week, xCount
from yt
) src
pivot
(
sum(xcount)
for week in ([1], [2], [3])
) pi...
JUnit Testing Exceptions [duplicate]
...xample == null) {
throw new NullPointerException();
}
//do fun things with valid example here
}
Then, when you run this JUnit test you will get a green bar:
@Test(expected = NullPointerException.class)
public void constructorShouldThrowNullPointerException() {
Example example ...
Remove a prefix from a string [duplicate]
...
Cool! Note: the behavior of the new function is exactly as in this answer (returning the string unchanged if it does not start with prefix)
– Elazar
May 27 at 23:50
...
How to use hex color values
...
How would you handle 123ABC? The compiler is burking at it not being a digit.
– Islam Q.
Mar 2 '16 at 6:28
1
...
Using a ListAdapter to fill a LinearLayout inside a ScrollView layout
...
I use following code which replicate adapter functionality with ViewGroup and TabLayout. Good thing about this is that if you change your list and bind again, it will only affect changed items:
Usage:
val list = mutableListOf<Person>()
layout.bindChildren(list, ...
Understanding :source option of has_one/has_many through of Rails
...'ve chosen to namespace the Dog::Breed, because we want to access Dog.find(123).breeds as a nice and convenient association.
Now, if we now want to create a has_many :dog_breeds, :through => :dogs association on Pet, we suddenly have a problem. Rails won't be able to find a :dog_breeds associati...
Get users by name property using Firebase
...:
Write to Firebase with a unique, known key:
ref.child('users').child('123').set({ "first_name": "rob", "age": 28 })
Append to lists with an auto-generated key that will automatically sort by time written:
ref.child('users').push({ "first_name": "rob", "age": 28 })
Listen for changes in data ...
Is JavaScript an untyped language?
...licit compiler interjection, the instruction will error during run-time.
"12345" * 1 === 12345 // string * number => number
Strongly typed means there is a compiler, and it wants you an explicit cast from string to integer.
(int) "12345" * 1 === 12345
In either case, some compiler's featur...
How to convert std::string to lower case?
...aracters allowed in the french language. For instance a string 'Test String123. É Ï\n' will be converted to : 'test string123. É Ï\n' although characters É Ï and their lower case couterparts 'é' and 'ï', are allowed in french. It seems that no solution for that was provided by other message...