JavaUtilList to NSArray?

[confile]

I have a JavaUtilList and want to transform it into an NSArray.

let userList:JavaUtilList = JavaUtilArrayList()

I could create an IOSObjectArray: 

let arr:IOSObjectArray = userList.toArray()

Now I want to have an NSArray of String

var list: [String] = ???

How can I transform a JavaUtilList or an IOSObjectArray into an NSArray?

 

[Tom Ball]

Create an NSMutableArray, then use a for loop to copy the list or array elements into it. Since j2objc's arrays and JRE collection classes support list comprehension, that can be as simple as:

+ (NSArray *)nsArrayFromList:(id<JavaUtilList>)list {

  NSMutableArray *result = [NSMutableArray array];

  for (id object in list) {

    [result addObject:object];

  }

  return result;

}

This is faster than it looks, since list comprehension uses NSFastEnumeration, which batches the copies.

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[confile]

Which class contains nsArrayFromList?

I get the error Type 'JavaUtilList' does not conform to protocol 'SequenceType'when I try your for loop.

[Tom Ball]

Are you trolling? It's an example I just wrote. I don't even know if it compiles, but thought it would at least demonstrate the idea. Apparently not. :(

[confile]

Is it valid to cast JavaUtilList to NSArray like: 

var arrayList:JavaUtilList = // some java arraylist list 

var list = arrayList as! NSArray

[Tom Ball]

No, unless you independently create a class that extends NSArray and implements java.util.List. Feel free to contribute such a class if you write it and want to share it with other j2objc developers.

[Matthew Pease]

+1 I'd like to see such a class. 

I'm just digging into j2objc.  Awesome tool!  But I did spend a fair amount of time figuring out all these new collection types.  Would be great if j2objc could emit objectiveC collection classes.  Though, after just a day using j2objc, I'm learning my way around the types.

Matt

[confile]

You could extend the class like this (in Swift): 

extension JavaUtilArrayList {

  

  func toNSArray<T>() -> [T] {

    var arr:[T] = []

    for var i:Int32=0; i < self.size(); i++ {

      arr.append(self.getWithInt(i) as! T)

    }

    return arr

  }

    

}

[kate.w...@ecrebo.com]

On Tuesday, 14 April 2015 19:16:26 UTC+1, Tom Ball wrote:
> Create an NSMutableArray, then use a for loop to copy the list or array elements into it. Since j2objc's arrays and JRE collection classes support list comprehension, that can be as simple as:
>
>
> + (NSArray *)nsArrayFromList:(id<JavaUtilList>)list {
>   NSMutableArray *result = [NSMutableArray array];
>   for (id object in list) {
>     [result addObject:object];
>   }
>   return result;
> }
>
>
> This is faster than it looks, since list comprehension uses NSFastEnumeration, which batches the copies.
>

Can confirm it both compiles and works, cribbed it into my Utils lib, saved me a few moments of typing.

[Lukasz Kalbarczyk]

How can I transform a JavaUtilList or an IOSObjectArray into an NSArray?

I will check it tomorrow, but I'm using something like that:

[NSArray arrayWithObjects: list count: [list size]]]

 (+ (instancetype)arrayWithObjects:(const id [])objects
                           count:(NSUInteger)count)

[Lukasz Kalbarczyk]

IOSObjectArray* ar = [objects toArray];
 [NSArray arrayWithObjects: ar->_buffer count: [objects size]]] // or [ar lenght]

[vtha...@gmail.com]

Look at my link on Stackoverflow:-

https://stackoverflow.com/questions/29633317/convert-javautillist-to-nsarray/59084220#59084220