Android SparseArray

이전 블로그에서 이전 함 (원본 글 2013/06/11 작성)

일반적으로 사용하는 자료구조 중 하나가

Map<Integer, String> 인데 data collision으로 인한 성능 문제로

Android에서는 SparseArray를 추천하고 있다.

하지만 Java Collection Interface를 지원하지는 않는데... 왜?!

[SparseArray]

http://developer.android.com/reference/android/util/SparseArray.html

public classSparseArrayextends Objectimplements Cloneable java.lang.Object    ↳ android.util.SparseArray<E>

[HashMap, SparseArray 사용]

별 차이는 없음.

http://android.okhelp.cz/sparsearray-instead-hashmap-android-example/

Old code with HashMap Map<Integer, Bitmap> _bitmapCache = new HashMap<Integer, Bitmap>(); private void fillBitmapCache() { _bitmapCache.put(R.drawable.icon, BitmapFactory.decodeResource(getResources(), R.drawable.icon)); _bitmapCache.put(R.drawable.abstrakt, BitmapFactory.decodeResource(getResources(), R.drawable.abstrakt)); _bitmapCache.put(R.drawable.wallpaper, BitmapFactory.decodeResource(getResources(), R.drawable.wallpaper)); _bitmapCache.put(R.drawable.scissors, BitmapFactory.decodeResource(getResources(), }   Bitmap bm = _bitmapCache.get(R.drawable.icon); New code with SparseArray SparseArray<Bitmap> _bitmapCache = new SparseArray<Bitmap>(); private void fillBitmapCache() { _bitmapCache.put(R.drawable.icon, BitmapFactory.decodeResource(getResources(), R.drawable.icon)); _bitmapCache.put(R.drawable.abstrakt, BitmapFactory.decodeResource(getResources(), R.drawable.abstrakt)); _bitmapCache.put(R.drawable.wallpaper, BitmapFactory.decodeResource(getResources(), R.drawable.wallpaper)); _bitmapCache.put(R.drawable.scissors, BitmapFactory.decodeResource(getResources(), }   Bitmap bm = _bitmapCache.get(R.drawable.icon);

[SparseArray iteration]

Collection interface 미지원으로 이렇게 loop을 사용해야 한다.. 귀찮아..

http://stackoverflow.com/questions/7999211/iterate-through-sparsearray

up vote83down voteaccepted seems I found the solution. I havent properly noticed keyAt(index) function. So I'll go with something like this int key = 0; for(int i = 0; i < sparseArray.size(); i++) { key = sparseArray.keyAt(i); // get the object by the key. Object obj = sparseArray.get(key); } share|improve this answer edited Feb 8 at 12:42 Baz 8,44351334 answered Nov 4 '11 at 9:12 Ruzanna 1,243414

[Map, HashMap 그리고 SparseArray 설명]

http://log.hanjava.net/post/30231660090/map-hashmap-sparsearray

[ParseArray Versus Hashmap 성능 비교]

http://www.javacodegeeks.com/2012/07/android-performance-tweaking-parsearray.html

Results SparseArray Results The SparseArray is a very quick data structure for sizes of 10,000 and less. If you are pulling data from your array considerably more than adding to it, you can get away with a size of 100,000. It starts to slow down a bit with the jump to 1,000, but nothing too surprising.

Hashmap Results