Pro Android Apps Performance Optimization

Caching Results

When computations are expensive, it may be a good idea to remember past results to make future requests faster. Using a cache is quite simple as it typically translates to the pseudo-code shown in Listing 1–10.

Listing 1–10. Using a Cache

    result = cache.get(n); // input parameter n used as key     if (result == null) {         // result was not in the cache so we compute it and add it         result = computeResult(n);         cache.put(n, result); // n is the key, result is the value     }     return result;

The faster recursive algorithm to compute Fibonacci terms yields many duplicate calculations and could greatly benefit from memoization. For example, computing the 50,000^th term requires computing the 25,000^th and 24,999 ...