Question

我有下面的代码，getBrand和calculateSum是一些返回值的函数。我想使用Java 8函数压缩此代码。如果可能的话，我想消除多个。可以使用Java 8函数吗？

import java.util.Collections;
import java.util.HashSet;
import java.util.Set;

public class Q56068628 {

    static class Brand {
        public Set<Location> locations() { return Collections.emptySet(); }
    }
    static class Location {}
    static class Product {}

    int getSum(int price, Product p){
        int sum = 0;
        if(price > 0){
           Brand b = getBrand(p); // getBrand takes type Product as argument
           if( b !=null){
              Set<Location> s = new HashSet<>();
              s.addAll(b.locations());
              for(Location l : s){
                sum = calculateSum(l, sum); /* calculateSum function takes location
                            argument and calculates sum. Sum value is replaced for
                          each for loop call */
              }
           }
        }
       return sum;
    }

    private Brand getBrand(Product p ){
    //// some code returns brand
        return null;
    }

     private int calculateSum(Location l, int sum ){
        //// some code returns an integer
        return 0;
     }

}

Answer 1

可能是这样，但是if语句通常比方法调用便宜，而且对于不了解这些API的人来说，它更容易阅读。您可以考虑的一项改进是：

private Optional<Brand> getBrand(Product p ){
   //...
   //something...
   if (condition) { return Optional.ofNullable(new Brand(p)); }
   else { return Optional.empty(); }
}

然后：

Optional<Brand> brand = getBrand(p);
if (brand.isPresent()) {
  Brand b = brand.get();
}

对null进行处理要安全得多。

使用Java 8函数而不是多个

1 个答案: