Use SparseArrayCompat for better performance

[isfaaghyth]

SparseArray can be used to replace HashMap when the key is a primitive type. There are some variants for different key/value types, even though not all of them are publicly available. let's take a look at the comparison:

SparseIntArray:

class SparseIntArray {
    int[] keys;
    int[] values;
    int size;
}

Class = 12 + 3 * 4 = 24 bytes
Array = 20 + 1000 * 4 = 4024 bytes
Total = 8,072 bytes

HashMap:

class HashMap<K, V> {
    Entry<K, V>[] table;
    Entry<K, V> forNull;
    int size;
    int modCount;
    int threshold;
    Set<K> keys
    Set<Entry<K, V>> entries;
    Collection<V> values;
}

Class = 12 + 8 * 4 = 48 bytes
Entry = 32 + 16 + 16 = 64 bytes
Array = 20 + 1000 * 64 = 64024 bytes
Total = 64,136 bytes

read more: https://speakerdeck.com/romainguy/android-memories?slide=90