Help with Java Maps

[Tiki]

The Sage API contains a method called GetMediaFilesWithImportPrefix(). It returns a map if the last parameter passed to it (GroupFolders) is TRUE, otherwise it returns a vector.

I want to iterate through this map or vector and remove any media files that reside in a specific path. I have no problem dealing with the vector, but not sure how to iterate through a map and remove the unwanted items.

If it matters, I want to do this in studio (though I think I will need to call some java methods to accomplish this).

Can anyone point me in the right direction?

[stuckless]

Maps are basically collections of Map.Entry objects where the Entry has a getKey() and a getValue()

if you don't care about the key, then you can simply iterate the map values by calling Map.values() (ie, java_util_Map_values(Map) ) which returns a collection of the values in the map without the keys.

If you need the keys... then you can use Map.entrySet() (ie, java_util_Map_entrySet(Map) ) which gives you a collection of Entry objects.

You can't remove from the map while you are iterating over it (at least not easily), so I'd build a second Map to hold the values that you want. As you interate over the Map.Entry objects, just add to the new map...
java_util_Map_put(NewMap, java_util_Map_Entry_getKey(MapEntry), java_util_Map_Entry_getValue(MapEntry))

Hope this helps you get started.

[Tiki]

Is it valid to iterate through the entry set as if it were an array?

Map = GetMediaFilesWithImportPrefix(a,b,c,d,e)
EntrySet = java_util_Map_entrySet(Map)

i=0
if i < Size(EntrySet) 'Start of Loop
  value = java_util_Map_Entry_getValue(EntrySet(i))
  key= java_util_Map_Entry_getKey(EntrySet(i))
  do something with value and key
  ...
  i=i+1
    if i< Size(EntrySet)  'End of Loop

This is how loops are generally accomplished in Studio code... not sure if I can do a java-style iterator

[PLUCKYHD]

Originally Posted by Tiki

Is it valid to iterate through the entry set as if it were an array?

Map = GetMediaFilesWithImportPrefix(a,b,c,d,e)
EntrySet = java_util_Map_entrySet(Map)

i=0
if i < Size(EntrySet) 'Start of Loop
  value = java_util_Map_Entry_getValue(EntrySet(i))
  key= java_util_Map_Entry_getKey(EntrySet(i))
  do something with value and key
  ...
  i=i+1
    if i< Size(EntrySet)  'End of Loop

This is how loops are generally accomplished in Studio code... not sure if I can do a java-style iterator

That should work fine to iterate it that way.

[stuckless]

You may need to use GetElement(EntrySet, i) or java_util_Set_get(EntrySet, i).

[Tiki]

Originally Posted by stuckless

You may need to use GetElement(EntrySet, i) or java_util_Set_get(EntrySet, i).

Thanks, I used GetElement(entrySet, i) and it seems to be working, though I still have some other issues I need to work out...

Thanks for the help.

[GKusnick]

Java Sets don't have a defined element order and don't implement the get(i) method, so I'm not sure what GetElement() would do with them. Possibly something along the lines of copying the set into a temporary array and returning the ith element of the array.

Sets are however Iterable, so it may be more formally correct to call the set's iterator() method and use the returned Iterator's hasNext() and next() methods to access successive elements.

[Tiki]

Originally Posted by GKusnick

Sets are however Iterable, so it may be more formally correct to call the set's iterator() method and use the returned Iterator's hasNext() and next() methods to access successive elements.

It's not immediately clear to me how this would be done in Studio code. I will have to think that one over a bit.

[stuckless]

Originally Posted by GKusnick

Java Sets don't have a defined element order and don't implement the get(i) method, so I'm not sure what GetElement() would do with them. Possibly something along the lines of copying the set into a temporary array and returning the ith element of the array.

Sets are however Iterable, so it may be more formally correct to call the set's iterator() method and use the returned Iterator's hasNext() and next() methods to access successive elements.

That's a good point Greg. I tend to take that for granted since I usually always iterate over the elements.

Originally Posted by Tiki

It's not immediately clear to me how this would be done in Studio code. I will have to think that one over a bit.

Does studio have a While loop syntax? If so, you get the iterator

Iterator = java_util_Set_iterator(EntrySet)

and then you can work on the objects until hasNext() is false

while (java_util_Iterator_hasNext(Iterator)) {
Item = java_util_Iterator_next(Iterator)
}

[Tiki]

Originally Posted by stuckless

Does studio have a While loop syntax? If so, you get the iterator

Iterator = java_util_Set_iterator(EntrySet)

and then you can work on the objects until hasNext() is false

while (java_util_Iterator_hasNext(Iterator)) {
Item = java_util_Iterator_next(Iterator)
}

No. The only conditional is "IF".

So, I think what I need to do in Studio is:

tempVids = new_java_util_HashMap()
entrySet = java_util_Map_entrySet(tempVids)
setIterator = java_util_Map_iterator(entrySet)

IF java_util_Iterator_hasNext(Iterator) 'This is the start of the loop
TRUE
curElement = java_util_Map_next(setIterator)
myValue = java_util_Map_Entry_getValue(curElement)
myKey = java_util_Map_Entry_getKey(curElement)
IF (some conditional code)
TRUE
java_util_Map_put(tempVids, myKey, MyValue)
IF java_util_Iterator_hasNext(Iterator) 'This is the end of the loop

---
Unfortunately, this doesn't work. Studio doesn't like the line "setIterator = java_util_Map_iterator(entrySet)"

[GKusnick]

Originally Posted by Tiki

Unfortunately, this doesn't work. Studio doesn't like the line "setIterator = java_util_Map_iterator(entrySet)"

You want java_util_Set_iterator(entrySet).

[Opus4]

Originally Posted by Tiki

The Sage API contains a method called GetMediaFilesWithImportPrefix(). It returns a map if the last parameter passed to it (GroupFolders) is TRUE, otherwise it returns a vector.

I want to iterate through this map or vector and remove any media files that reside in a specific path. I have no problem dealing with the vector, but not sure how to iterate through a map and remove the unwanted items.

You could consider filtering your list of media files first, then sending that list as the first parameter of GetMediaFilesWithImportPrefix().

- Andy

[Tiki]

Originally Posted by Opus4

You could consider filtering your list of media files first, then sending that list as the first parameter of GetMediaFilesWithImportPrefix().

- Andy

That's actually a really good idea. I thought that 1st parameter had to be a media mask, but I see after re-reading the API doc, that it can alternatively be an array/collection of MediaFile objects.

[stuckless]

Originally Posted by Tiki

Unfortunately, this doesn't work. Studio doesn't like the line "[/COLOR][/COLOR]setIterator = java_util_Map_iterator(entrySet)"

Unfortunately, I think the studio syntax might be a bit odd, but I think it would be
Iterator = java_util_Set_iterator(java_util_Map_entrySet(Map))

In java..
Iterator = Map.entrySet().iterator()

But I don't think there is an easier way to do that in Studio.

[PLUCKYHD]

Originally Posted by stuckless

Unfortunately, I think the studio syntax might be a bit odd, but I think it would be
Iterator = java_util_Set_iterator(java_util_Map_entrySet(Map))

In java..
Iterator = Map.entrySet().iterator()

But I don't think there is an easier way to do that in Studio.

actually I think it has to be in studio

Iterator =new_java_util_Set_iterator(java_util_Map_entrySet(Map))

I think you have to have the new but can't remember man I am glad I stopped doing that stuff in studio

[GKusnick]

Originally Posted by PLUCKYHD

I think you have to have the new but can't remember

No, you don't need new because you're not instantiating the Iterator class; you're calling the iterator() method, which returns an instance of that class. (Any necessary instantiation presumably happens inside the method implementation.)