java My代码违反了DRY原则,但不确定如何进行重构
我对OOP非常陌生,并且用Java编写了一些用于在不同长度单位之间转换双精度值的类,但是我意识到,让类似的类做基本相同的事情违反了DRY原则
问题1:在这种情况下,创建度量单位的更好解决方案是什么
问题2:我想在“lengthConverter”类中完成所有转换,但我意识到它是在多个类之间分割的。将“convertTo”方法从“Feet”类放到“lengthConverter”类中,对于每一个额外的单元,这样做有意义吗
public class LengthConverter {
private Inches inches = new Inches();
private Feet feet = new Feet();
private Meters meters = new Meters();
private Miles miles = new Miles();
private Millimeters millimeters = new Millimeters();
private Centimeters centimeters = new Centimeters();
private Kilometers kilometers = new Kilometers();
private Yards yards = new Yards();
public LengthConverter() {
}
public double convert(String origUnit, double length, String toUnit) {
double result = 0;
switch (origUnit) {
case "cm":
centimeters.setLength(length);
result = centimeters.convertTo(toUnit);
break;
case "ft":
feet.setLength(length);
result = feet.convertTo(toUnit);
break;
case "in":
inches.setLength(length);
result = inches.convertTo(toUnit);
break;
case "km":
kilometers.setLength(length);
result = kilometers.convertTo(toUnit);
break;
case "m":
meters.setLength(length);
result = meters.convertTo(toUnit);
break;
case "mi":
miles.setLength(length);
result = miles.convertTo(toUnit);
break;
case "mm":
millimeters.setLength(length);
result = millimeters.convertTo(toUnit);
break;
case "yd":
yards.setLength(length);
result = yards.convertTo(toUnit);
break;
default:
System.out.println("Error: incorrect input");
}
return result;
}
public class Feet {
final private double FOOT_TO_CM = 30.48;
final private double FOOT_TO_INCH = 12;
final private double FOOT_TO_KM = 0.000305;
final private double FOOT_TO_METER = 0.3048;
final private double FOOT_TO_MILE = 0.000189;
final private double FOOT_TO_MM = 304.8;
final private double FOOT_TO_YD = 0.333333;
final private double FOOT = 1;
private double length;
public Feet() {
}
public void setLength(double length) {
this.length = length;
}
public double convertTo(String unit) {
double result = 0;
switch (unit) {
case "in":
result = length * FOOT_TO_INCH;
break;
case "m":
result = length * FOOT_TO_METER;
break;
case "mi":
result = length * FOOT_TO_MILE;
break;
case "mm":
result = length * FOOT_TO_MM;
break;
case "cm":
result = length * FOOT_TO_CM;
break;
case "km":
result = length * FOOT_TO_KM;
break;
case "yd":
result = length * FOOT_TO_YD;
break;
case "ft":
result = length * FOOT;
break;
}
return result;
}
}
# 1 楼答案
您可以使用Java枚举。看看TimeUnit(特别是TimeUnit.convert(long,TimeUnit))的转换。该源代码位于GitHub上