Common answers to the measured unit API in the Java class library

Common answers to the measured unit API in the Java class library The metering unit is one of the concepts commonly used in computer programs. In the Java class library, there are special APIs for processing the measurement unit.This article will answer some common questions about the API in the measurement unit in the Java class library, and provide the corresponding code examples. Question 1: What are the APIs used in the Java class library to handle the measurement unit? After Java SE 8, a new JSR 363 standard was introduced, which included APIs for processing the measurement unit.The main API includes: 1. `javax.measure`: Define the interfaces and classes of measurement units and measurement values. 2. `javax.measure.quantity`: Define the interfaces and classes of various physical quantities (such as length, quality, time, etc.). 3. Javax.measure.unit`: Define the interfaces and classes of various units (such as rice, kg, second, etc.). 4. `javax.measure.Converter`: Define the interfaces and classes of conversion between units. Question 2: How to create an object of a measurement unit? First, you need to import related classes and interfaces: import javax.measure.*; import javax.measure.quantity.*; import javax.measure.unit.*; Then, the unit interface and class can be used to create the object of the measurement unit.For example, to create a metering unit object that represents length, you can use `si.meter`: Unit<Length> meter = SI.METER; Question 3: How to transition between metering units? The `converter` interface in the Java class library and its implementation class are used to process conversion between metering units.You can use the `TO ()` method to convert one metering value to the metering value of another unit.For example, convert rice to feet: double valueInMeter = 5.0; UnitConverter meterToFootConverter = SI.METER.getConverterTo(NonSI.FOOT); double valueInFoot = meterToFootConverter.convert(valueInMeter); Question 4: How to perform numerical operations of measurement value? The measurement value class in the Java class library `Measure` provides a method of numerical operations on the measurement value.For example, two measured values can be added: Measure<Double, Length> length1 = Measure.valueOf(5.0, SI.METER); Measure<Double, Length> length2 = Measure.valueOf(3.0, SI.METER); Measure<Double, Length> sum = length1.add(length2); Question 5: How to format the output of the measurement value? You can use the output of the measurement value to format the measurement value of the `MeaSurementFormat` class.For example, the formatting of a length value into a string: Measure<Double, Length> length = Measure.valueOf(5.0, SI.METER); MeasurementFormat format = MeasurementFormat.getInstance(Locale.CHINA); String formattedString = format.format(length); This article answers some common problems about the API in the measurement unit in the Java class library, and provides corresponding code examples.It is hoped that this article can help readers better understand and apply the measured unit API in the Java class library.