Question

   import java.util.ArrayList;
   import java.util.List;

   public class Apple {
        private static String color;
        private static int weight;
        public Apple(String color, int weight){
            this.color = color;
            this.weight = weight;
        }
        public int getWeight(){
            return weight;
        }
        public String getColor(){
        return color;
        }
        public interface AppleFormatter{
            String accept(Apple a);
        }
        public static class AppleFancyFormatter implements AppleFormatter{
            public String accept(Apple apple){
                String characteristic = apple.getWeight() > 150 ? "heavy" :     "light";
                return "A " + characteristic + " " + apple.getColor() + "  apple";
            }
        }
        public static class AppleSimpleFormatter implements AppleFormatter{
            public String accept(Apple apple){
                return "An apple of " + apple.getWeight() + "g";
            }
        } 
        public static void prettyPrintApple(List<Apple> inventory,  AppleFormatter formatter){
            for(Apple apple: inventory){
                String output = formatter.accept(apple);
                System.out.println(output);
            }
        }
        public static void main(String[] args){
            List<Apple> arrayList = new ArrayList<>();
            Apple app1 = new Apple("green", 155);
            Apple app2 = new Apple("yellow", 160);
            Apple app3 = new Apple("red", 130);
            arrayList.add(app1);
            arrayList.add(app2);
            arrayList.add(app3);

            prettyPrintApple(arrayList, new AppleFancyFormatter());
            prettyPrintApple(arrayList, new AppleSimpleFormatter());

        }
    }

以下代码打印：一个浅红色的苹果一个浅红色的苹果一个浅红色的苹果一个130克的苹果一个130克的苹果一个130克的苹果

我注意到了我的数组不能正确迭代的倾向，但是我创建的最后一个对象不断被打印出来。我不知道为什么会这样。我错过了什么？enter code here

Answer 1

你的领域是静态的！

 private static String color;
 private static int weight;

所以所有的苹果都有相同的颜色和重量！删除static关键字，一切正常！

打印ArrayList时出现冗余结果

1 个答案: