Performance

Composite Recipes

Recipes that include further recipes, often including the individual recipes below.

• Apply Kotlin performance idioms
• Collapse filter \{ p \}.<terminal>() chains
• Collapse sorted().first/last() and reversed().first/last() chains
• Find Sequence/List pipeline shape smells
• Find collection construction inside loops
• Find expensive allocations inside collection lambdas
• Find expensive allocations on hot paths
• Improve performance of Kotlin code
• Use primitive mutable<Int|Long|Float|Double>StateOf in Compose

Recipes

• Find Base64.getDecoder() calls inside loops
• Find BigDecimal("...") allocations inside loops
• Find BigInteger("...") allocations inside loops
• Find BigInteger.valueOf(long) calls inside loops
• Find Calendar.getInstance() calls inside loops
• Find Charset.forName(...) calls inside loops
• Find Class.forName calls inside loops
• Find DateTimeFormatter.ofPattern allocations inside loops
• Find File(...).bufferedReader() calls inside loops
• Find Gson() allocations inside collection lambdas
• Find Gson() allocations inside loops
• Find Jackson ObjectMapper() allocations inside collection lambdas
• Find Jackson ObjectMapper() allocations inside loops
• Find Locale(...) allocations inside loops
• Find LoggerFactory.getLogger calls inside collection lambdas
• Find LoggerFactory.getLogger calls inside loops
• Find MessageDigest.getInstance calls inside loops
• Find Optional.get() calls inside loops
• Find Pattern.compile allocations inside loops
• Find Pattern.compile calls inside collection lambdas
• Find Regex allocations inside collection lambdas
• Find Regex allocations inside loops
• Find SimpleDateFormat allocations inside loops
• Find String.format calls inside collection lambdas
• Find String.format calls inside loops
• Find URI("...") allocations inside loops
• Find URL("...") allocations inside loops
• Find for (i in xs.indices) \{ val x = xs[i] \} patterns
• Find graphics allocations inside View.onDraw
• Find graphics allocations inside View.onLayout
• Find graphics allocations inside View.onMeasure
• Find iteration-shape smells
• Find listOf(...) calls inside loops
• Find long List pipelines that should use Sequence
• Find mutableListOf<T>() allocations inside loops
• Find mutableMapOf<K, V>() allocations inside loops
• Find s = s + "..." string concatenation inside loops
• Find seq.toList().map \{ ... \} patterns
• Find string-allocation smells
• Use any \{ predicate \} instead of filter \{ predicate \}.any()
• Use any \{ predicate \} instead of filter \{ predicate \}.isNotEmpty()
• Use count \{ predicate \} instead of filter \{ predicate \}.count()
• Use filterNotTo(mutableListOf(), p) instead of filterNot(p).toMutableList()
• Use filterTo(mutableListOf(), p) instead of filter(p).toMutableList()
• Use first \{ predicate \} instead of filter \{ predicate \}.first()
• Use first() instead of reversed().last()
• Use firstNotNullOf \{ f \} instead of mapNotNull \{ f \}.first()
• Use firstNotNullOfOrNull \{ f \} instead of mapNotNull \{ f \}.firstOrNull()
• Use firstOrNull \{ predicate \} instead of filter \{ predicate \}.firstOrNull()
• Use flatMapTo(mutableListOf(), f) instead of flatMap(f).toMutableList()
• Use last \{ predicate \} instead of filter \{ predicate \}.last()
• Use last() instead of reversed().first()
• Use lastOrNull \{ predicate \} instead of filter \{ predicate \}.lastOrNull()
• Use mapNotNull \{ f \} instead of map \{ f \}.filterNotNull()
• Use mapTo(mutableListOf(), f) instead of map(f).toMutableList()
• Use max() instead of sorted().last()
• Use max() instead of sortedDescending().first()
• Use maxBy \{ selector \} instead of sortedBy \{ selector \}.last()
• Use maxOf \{ selector \} instead of map \{ selector \}.max()
• Use min() instead of sorted().first()
• Use min() instead of sortedDescending().last()
• Use minBy \{ selector \} instead of sortedBy \{ selector \}.first()
• Use minOf \{ selector \} instead of map \{ selector \}.min()
• Use mutableDoubleStateOf instead of mutableStateOf<Double> in Compose
• Use mutableFloatStateOf instead of mutableStateOf<Float> in Compose
• Use mutableIntStateOf instead of mutableStateOf<Int> in Compose
• Use mutableLongStateOf instead of mutableStateOf<Long> in Compose
• Use none \{ predicate \} instead of filter \{ predicate \}.isEmpty()
• Use none \{ predicate \} instead of filter \{ predicate \}.none()
• Use sb.length instead of sb.toString().length
• Use single \{ predicate \} instead of filter \{ predicate \}.single()
• Use singleOrNull \{ predicate \} instead of filter \{ predicate \}.singleOrNull()
• Use sortedByDescending \{ f \} instead of sortedBy \{ f \}.reversed()
• Use sortedDescending() instead of sorted().reversed()
• Use sumOf \{ selector \} instead of map \{ selector \}.sum()