为什么我的Java流代码输出类似“streamsapi.product@5b480cf9”的值？ [重复]

Question

我正在检查此代码以使用流 API 在集合数据中进行过滤。
我应该得到满足我的条件的两种产品的清单
但我得到解密格式的输出。

package streamsapi;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.stream.Collectors;

public class StreamFilter {

    
    public static void main(String[] args) {
        
        // TODO Auto-generated method stub
        /*
         * List<product>list = new ArrayList<product>(); for (product product :
         * getProducts()) { if(product.getPrice()>2500f) { list.add(product); }
         * 
         * } for (product product : list) { System.out.println(product); }
         */
        
        
          List<product>list2 = getProducts().stream() .filter((product)->
          product.getPrice() > 2500f) .collect(Collectors.toList());
          list2.forEach(System.out::println);
         
    }
    private static List<product> getProducts(){
    List<product>ProductsList = new ArrayList<product>();
    ProductsList.add(new product(1,"hp",2500f));
    ProductsList.add(new product(2,"Dell",3500f));
    ProductsList.add(new product(3,"Asus",4500f));
    return ProductsList;
    
    }}
    class product{
        private int id;
        private String name;
        private float price;
        public product(int id, String name, float price) {
            super();
            this.name = name;
            this.id = id;
            this.price = price;
        }
        public String getName() {
            return name;
        }
        public void setName(String name) {
            this.name = name;
        }
        public int getId() {
            return id;
        }
        public void setId(int id) {
            this.id = id;
        }
        public float getPrice() {
            return price;
        }
        public void setPrice(float price) {
            this.price = price;
        }
        
    }

我的输出是：

streamsapi.product@3feba861
streamsapi.product@5b480cf9

Answer 1

我认为你只需要重写

toString

类中的

Product

，以便

System.out::println

可以打印对象内容而不是引用

class product{
    ...

    @Override
    public String toString() {
      return "Product{" +
          "id=" + id +
          ", name=" + name +
          ", price='" + price + '\'' +
          '}';
    }
}