[英]How can I simplify if else using java 8 aproach
public Pair<String, String> getSalesChannelDisplayData(DiscountRule rule, List<SalesChannelDto> allSalesChannels) {
String salesChannelDisplayNames = "";
String salesChannelDefaultCountryCodes = "";
Set<String> storeCodes = new HashSet<>();
if(rule.getConditions() != null) {
for (Condition condition : rule.getConditions()) {
if (condition instanceof ValueCondition) {
if (((ValueCondition) condition).getField() == Field.SALES_CHANNEL) {
Set<String> salesChannelIds = new HashSet<>();
if(((ValueCondition) condition).getOperator().equals(Operator.IN)){
salesChannelIds = ((ValueCondition) condition).getValues();
}else if (((ValueCondition) condition).getOperator().equals(Operator.NOT_IN)) {
salesChannelIds = allSalesChannels.stream().map(SalesChannelDto::getId).collect(Collectors.toSet());
salesChannelIds.removeAll(((ValueCondition) condition).getValues());
}
for (String salesChannelId : salesChannelIds) {
SalesChannelDto salesChannel = Beans.find(allSalesChannels, s-> s.getId().equals(salesChannelId));
salesChannelDisplayNames += salesChannel.getDisplayName() + ", ";
storeCodes.add(salesChannel.getDefaultCountryCode());
}
}
}
}
if (salesChannelDisplayNames.length()>1) {
salesChannelDisplayNames = salesChannelDisplayNames.substring(0,salesChannelDisplayNames.length()-2);
salesChannelDefaultCountryCodes = Joiner.on(", ").join(storeCodes);
}
return new Pair<>(salesChannelDisplayNames, salesChannelDefaultCountryCodes);
}
我想使用 java stream API 来简化上面的代码。是否可以用 java 8 方法替换 if, else if?
stream API 不是简化代码的好选择。 您可以修改代码中的某些部分。
1- 不需要检查rule.getConditions()
是否无效。
if(rule.getConditions() != null) {...}
2- 不要重复自己: ((ValueCondition) condition)
相反,您可以为其定义一个变量并使用它。
ValueCondition vCondition = (ValueCondition) condition;
3- 代替连接salesChannelDisplayNames
声明一个List<String> salesChannelNames = new ArrayList<>();
并将channelName添加到其中。
salesChannelNames.add(salesChannel.getDisplayName());
最后使用String.join(",", salesChannelNames)
在它们之间添加,
delimeter。
这是您可以试用的示例。 我试图完全消除 if-else。
public class FunctionalIfElse {
public static void main(String[] args) {
Product product1 = new Product(1, "Audi A8");
String category1 = "car";
System.out.println(ProductProxy.getEnrichedProduct.apply(product1, category1).toString());
Product product2 = new Product(2, "OnePlus 8 Pro");
String category2 = "mobile";
System.out.println(ProductProxy.getEnrichedProduct.apply(product2, category2).toString());
Product product3 = new Product(3, "Macbook Pro");
String category3 = "laptop";
System.out.println(ProductProxy.getEnrichedProduct.apply(product3, category3).toString());
Product product4 = new Product(4, "Emaar Palm Heights");
String category4 = "home";
System.out.println(ProductProxy.getEnrichedProduct.apply(product4, category4).toString());
}
}
@AllArgsConstructor
@Data
class Product {
private int productId;
private String productName;
}
class ProductProxy {
static BiFunction<Product, String, Product> getEnrichedProduct = (inputProduct, category) -> {
AtomicReference<Product> outputProduct = new AtomicReference<>();
Objects.requireNonNull(category, "The category is null");
Predicate<String> checkIsCar = productCategory -> productCategory.equalsIgnoreCase("car") ? true : false;
Predicate<String> checkIsMobile = productCategory -> productCategory.equalsIgnoreCase("mobile") ? true : false;
Predicate<String> checkIsLaptop = productCategory -> productCategory.equalsIgnoreCase("laptop") ? true : false;
Optional.ofNullable(category).filter(checkIsCar).map(input -> ProductService.enrichProductForCar.apply(inputProduct)).map(Optional::of).ifPresent(returnedProduct -> outputProduct.set(returnedProduct.get()));
Optional.ofNullable(category).filter(checkIsMobile).map(input -> ProductService.enrichProductForMobile.apply(inputProduct)).map(Optional::of).ifPresent(returnedProduct -> outputProduct.set(returnedProduct.get()));
Optional.ofNullable(category).filter(checkIsLaptop).map(input -> ProductService.enrichProductForLaptop.apply(inputProduct)).map(Optional::of).ifPresent(returnedProduct -> outputProduct.set(returnedProduct.get()));
Optional.ofNullable(outputProduct.get()).orElseThrow(() -> new RuntimeException("This is not a valid category"));
return outputProduct.get();
};
}
class ProductService {
static Function<Product, Product> enrichProductForCar = inputProduct -> {
inputProduct.setProductName(inputProduct.getProductName() + ":Car");
return inputProduct;
};
static Function<Product, Product> enrichProductForMobile = inputProduct -> {
inputProduct.setProductName(inputProduct.getProductName() + ":Mobile");
return inputProduct;
};
static Function<Product, Product> enrichProductForLaptop = inputProduct -> {
inputProduct.setProductName(inputProduct.getProductName() + ":Laptop");
return inputProduct;
};
}
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