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问题描述
我有195个ifs的方法。这是一个简短的版本:
I have a method with 195 ifs. Here is a shorter version:
private BigDecimal calculateTax(String country, BigDecimal amount) throws Exception { if(country.equals("POLAND")){ return new BigDecimal(0.23).multiply(amount); } else if(country.equals("AUSTRIA")) { return new BigDecimal(0.20).multiply(amount); } else if(country.equals("CYPRUS")) { return new BigDecimal(0.19).multiply(amount); } else { throw new Exception("Country not supported"); } }我可以更改if开关:
private BigDecimal calculateTax(String country, BigDecimal amount) throws Exception { switch (country) { case "POLAND": return new BigDecimal(0.23).multiply(amount); case "AUSTRIA": return new BigDecimal(0.20).multiply(amount); case "CYPRUS": return new BigDecimal(0.19).multiply(amount); default: throw new Exception("Country not supported"); } },但是195个案例仍然很长。如何改善该方法的可读性和长度?在这种情况下哪种模式是最好的?
but 195 cases is still so long. How could I improve readability and length of that method? What pattern would be the best in this case?
推荐答案创建 Map< String,Double> ,将国家/地区名称映射到相应的税率:
Create a Map<String,Double> that maps country names to their corresponding tax rates:
Map<String,Double> taxRates = new HashMap<> (); taxRates.put("POLAND",0.23); ...使用该地图如下:
private BigDecimal calculateTax(String country, BigDecimal amount) throws Exception { if (taxRates.containsKey(country)) { return new BigDecimal(taxRates.get(country)).multiply(amount); } else { throw new Exception("Country not supported"); } }更多推荐
如何使用许多if语句提高方法的可读性和长度?
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