让参数具有形为能力

╰+攻爆jí腚メ 2022-12-22 02:28 108阅读 0赞

客户的需求总是变化的，有时候一开始比较简单，后来提出的越来越复杂，我们需要良好的设计才能应对变化不断的需求。我们通过一些例子，去了解下吧。

1.  一开始需求比较简单，查询苹果颜色为"green"
    
        public class FilterApple { 
            public static List<Apple> findGreenApple(List<Apple> apples){ 
                List<Apple> greenApples = new ArrayList<>();
        
                for (Apple apple: apples){ 
                    if ("green".equals(apple.getColor())){ 
                        greenApples.add(apple);
                    }
                }
        
                return greenApples;
            }
        
            public static void main(String[] args) { 
                List<Apple> apples = Arrays.asList(new Apple(120, "green"),
                        new Apple(110, "yellow"),
                        new Apple(160, "green"),
                        new Apple(140, "red"));
        
               List<Apple> greenApples =  findGreenApple(apples);
        }
2.  现要求查询苹果颜色可能比较灵活
    
        public static List<Apple> findColorApple(List<Apple> apples, String color){ 
            List<Apple> newApples = new ArrayList<>();
        
            for (Apple apple: apples){ 
                if (color.equals(apple.getColor())){ 
                    newApples.add(apple);
                }
            }
        
            return newApples;
        }
3.  需求进一步，查询条件除了颜色，还有重量
    
        public class FilterApple { 
            public interface AppleFilter{ 
                boolean filter(Apple apple);
            }
        
            public static List<Apple> findFilterApple(List<Apple> apples, AppleFilter appleFilter){ 
                List<Apple> newApples = new ArrayList<>();
        
                for (Apple apple: apples){ 
                    if (appleFilter.filter(apple)){ 
                        newApples.add(apple);
                    }
                }
        
                return newApples;
            }
        	
        	public static class GreenAnd150WeightFiler implements  AppleFilter{ 
        
                @Override
                public boolean filter(Apple apple) { 
                    return apple.getColor().equals("green") && apple.getWeight() >= 150;
                }
        	}
        	
            public static void main(String[] args) { 
                List<Apple> apples = Arrays.asList(new Apple(120, "green"),
                        new Apple(110, "yellow"),
                        new Apple(160, "green"),
                        new Apple(140, "red"));
        
        
                List<Apple> newApples =  findFilterApple(apples, new GreenAnd150WeightFiler());
            }
        }

4.使用匿名内部类的方式，实现上面一种

List<Apple> newApples =  findFilterApple(apples, new AppleFilter(){ 
    	
    	            @Override
    	            public boolean filter(Apple apple) { 
    	                return apple.getColor().equals("red") && apple.getWeight() >= 110;
    	            }
    	        });

**还有没有其它更灵活、更简结的方法？下一章节，我们将介绍到**