I have an ArrayList of LongArrays, each of size 2. I am trying to use the built-in 'indexOf' method to find the index of a specific array of longs, and I can't figure out why the code says the array of longs I'm searching for isn't found. See the below screen shot of a debugging session where try to evaluate finding 'longArrayOf(0L,5L)' in the ArrayList. In my mind, longArrayOf(0L,5L) is clearly the first element in the cardHierarchy array. Can the 'indexOf' function not be used for finding arrays? Can anyone suggest an alternate method?
indexOf uses Object.equals() when you pass arrays, which compares by reference address which is different for the LongArray passed to indexOf and the one present in cardHierarchy.
Change it to
cardHierarchy.indexOfFirst { it.contentEquals(longArrayOf(0L, 5L)) }
Related
I'm tryna add to HashMap Array of Strings but instead of normal Array of String I see only address in memory of String in console.
val map = mapOf<String, Array<String>>()
val list = listOf("sport")
val array = list.toTypedArray()
map["key"] to array
And Array after this operation converts in smth like this — [Ljava.lang.String;#518ed9b4
But expected to see this kind of behavior:
map["key"] -> array("sport")
What's the problem might be with this sample of code?
Arrays in Java/Kotlin don't have a good automatic conversion to strings (technically, their implementation of toString()). What you see is your array, but instead of showing the contents, it only says it is an array of strings and shows the memory address.
To show the contents of an array you can use builtin contentToString() extension or wrap it into a list:
println(arrayOf("sport").contentToString())
println(arrayOf("sport").asList())
BTW, I believe there is a mistake in your example. map["key"] to array doesn't do anything, it should be probably map["key"] = array. Also, map in your example is read-only, you can't add items to it. However, as you already got to the point you print an array, I assume your real code is a little different.
So, looking for advice on how to fix a situation or maybe a better way to program it.
I'm using iteration to build a complicated string from key:value pairs in an unordered_map. To make this work, I'm iterating through the map to find specific items, then sending a search term to an outside function to create the string. The outside function uses its own iterator to search the same unordered_map for the passed search term, then creates the string, then erases the entries that it referenced. The problem, I believe, is that although the outside function's iterator is still valid because it called the erase function, the iterators in the main function are now invalidated and throwing an out of range error. Is there a way to reset the iterators or send them to the next valid key:value pair when they become invalidated in order to avoid the error?
The code is a mess (mostly because I'm still discovering C++) and it might be possible to use recursion to accomplish this, but I wasn't able to get recursion to work correctly.
I can post the code, but without understanding the inputs and required outputs, it's likely not going to help explain anything, so for now, I'll just leave the question as-is: is there a way to "re-validate" invalidated iterators?
I was able to resolve the issue by redefining each of the iterators once the scope of control returned back to them. For the last iterator (in the outside function) that deleted individual key:value pairs from the unordered_map, I used:
if (it != map.end()) it = map.erase(it);
This forces the iterator to move to the next valid key:value pair after the erasure.
That worked for the end of the line, but didn't work once control was returned to each of the previous iterators. In those case, the iterators were invalidated when the outside function erased a key:value pair. So as control returned to an iterator, I included the following line before it looped back for increment:
if (it != map.end()) it = map.begin();
It seems to have resolved all of the issues, though I'm sure there's a better way to handle it.
I currently write some code to decode string using NSStringEncoding.
And I'd like to decode that string using all value of NSStringEncoding.
But I don't know how to get all value of NSStringEncoding.
I checked this article, but values of NSStringEncoding it not continuous,
so I'm looking for better solution.
looping through enum values
Anyone have good idea??
You can use NSString's class method availableStringEncodings which:
Returns a zero-terminated list of the encodings string objects support in the application’s environment.
Described another way a "zero-terminated list" is a pointer to a C-array. You can iterate over this array.
HTH
I can across a copy methods from charTermAttr from the org.apache.lucene.analysis.tokenattributes.CharTermAttribute library.
Can anyone explain what copyBuffer and buffer does for charTermAttr? The documentation isn't very clear. If you could provide an example that would be great too!
CharTermAttributeImpl keeps internally a char array and a length variable that represents the internal term.
The copyBuffer method writes over this array by using the char array provided with the respective offset and length params.
The buffer method returns the internal array that you can directly modify. Additionally, you can get the term representation as a string by calling the attribute's toString method
Have a look at the javadocs for more details: http://lucene.apache.org/core/4_9_0/core/org/apache/lucene/analysis/tokenattributes/CharTermAttribute.html
I feel quite silly asking this, but I couldn't find a definite answer anywhere. in vb.net, how are the array elements defined (if they are defined) for, for example:
Dim myarray(5) as int
does, at this point in time, myarray(3) for example have a defined value? If so, what is it?
From the MSDN documentation for the Dim statement:
If you declare the length of an array but do not initialize its
elements, each element is initialized as if it were a separate
variable.
Essentially, value types will be initialized to their default value (0 for numeric types), and reference types will be initialized to Nothing.