Warning shows when i use Hash Map In android(Use new SparseArray<String>)

Use new SparseArray<String>(...) instead for better performance

You are getting this warning because of reason described here.

SparseArrays map integers to Objects. Unlike a normal array of Objects, there can be gaps in the indices. It is intended to be more efficient than using a HashMap to map Integers to Objects.

Now

how i use SparseArray ?

You can do it by below ways:

1. HashMap way:

   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);
   

2. SparseArray way:

   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);
   

Hope it Will Help.

SparseArray is used when you are using an Integer as a key.

When using the SparseArray, the key will stay as a primitive variable at all times unlike when you use the HashMap where it is required to have a Object as a key which will cause the int to become an Integer object just for a short time while getting the object in the map.

By using the SparseArray you will save the Garbage Collector some work.

So use just like a Map<Integer,String>.

It's a hint that there is a better data structure for your code.

That hint is from Lint. You usually get it when you have a HashMap of integers to something else.

Its biggest advantage is to treat the integer key as a primitive. In other words, it won't covert to an Integer (the Java object) to use it as a key.

This is a big deal when using large maps. HashMap will result in the creation of many, many Integer objects in that case.

See a few more pieces of information here.