The performance optimization skills

The performance optimization skills When developing Java applications, the use of the measured unit API (Unit API) can easily convert and calculate the unit.However, if you do not pay attention to performance optimization, these operations may become the bottleneck of the application.This article will introduce some performance optimization skills to help you improve the execution efficiency of the program when using the API of the measurement unit. 1. Choose the right unit The measured unit API provides a large number of unit types, such as length, weight and time.When using it, choose the most suitable unit according to actual needs.Choosing the right unit can reduce the conversion operation in the calculation, thereby improving performance. For example, if you need to process length, you can choose Meter as the basic unit to avoid frequent conversion between the units. Unit<Length> meter = SI.METER; Unit<Length> kilometer = SI.KILOMETER; // Good approach: Use rice as a basic unit for calculation double distance = 1000.0; // unit: rice double lengthInKilometer = meter.to(kilometer).convert(distance); System.out.println (lengthinkilometer + "kilometer"); // Not recommended: Frequent conversion of length units double lengthInMile = kilometer.to(NonSI.MILE).convert(distance); System.out.println (lengthinnmile + "Eri"); 2. cache unit The creation process of the metering unit may be relatively time -consuming. In order to reduce the creation and destruction of the object, the common unit objects are commonly used through cache.The `Unit` class in the Java class library is safe and can be shared by multiple threads. // Caches commonly used units Map<String, Unit<Length>> unitCache = new ConcurrentHashMap<>(); unitCache.put("meter", SI.METER); unitCache.put("kilometer", SI.KILOMETER); // Use the cache unit Unit<Length> meter = unitCache.get("meter"); Unit<Length> kilometer = unitCache.get("kilometer"); // Use the unit for calculation double distance = 1000.0; // unit: rice double lengthInKilometer = meter.to(kilometer).convert(distance); System.out.println (lengthinkilometer + "kilometer"); 3. Batch operation If a set of data is needed, you can consider using batch operations to avoid repeatedly calling the conversion method in the cycle. Unit<Length> meter = SI.METER; Unit<Length> kilometer = SI.KILOMETER; double [] distances = {1000.0, 2000.0, 3000.0, 4000.0}; // Unit: rice // Batch conversion unit UnitConverter meterToKilometer = meter.getConverterTo(kilometer); double[] lengthsInKilometer = meterToKilometer.convert(distances); for (double length : lengthsInKilometer) { System.out.println (length + "kilometer"); } 4. Avoid unnecessary accuracy processing The measured unit API supports custom accuracy and can set accuracy through the `mathContext` class.However, if you do not need to calculate the results, you can avoid using the `mathContext` to improve performance. Unit<Length> meter = SI.METER; Unit<Length> kilometer = SI.KILOMETER; double distance = 1000.0; // unit: rice // No need to calculate accurately, do not use mathcontext double lengthInKilometer = meter.to(kilometer).convert(distance); System.out.println (lengthinkilometer + "kilometer"); // Need to calculate accurately, use mathConext double preciseLengthInKilometer = meter.to(kilometer).withMathContext(MathContext.DECIMAL64).convert(distance); System.out.println (Precislengthinkilometer + "kilometer"); Summarize: The use of the measurement unit API can easily convert unit conversion and calculations, but still need to pay attention to performance optimization.Choose the right unit, cache unit object, batch operation, and avoid unnecessary accuracy treatment according to actual needs.Through reasonable application of these techniques, the execution efficiency of the Java application in terms of measurement unit processing can be improved.