如何返回相应的项目作为一个数组在java[重复]

Question

在下面的代码中，我试图实现getItemByManufacturer方法，该方法应该返回我们测试的制造商的项目数组。我曾尝试获取特定制造商的项目数组，但哈希代码正在打印。为什么呢？我也重写了toString方法。任何帮助都将不胜感激。

public class Item{
    
    private long serialNumber;
    private String itemName;
    String manufacturer;
    private int warrantyDays;
    private double rating;

Item( String itemName,String manufacturer,long serialNumber,double rating){
        this.serialNumber = serialNumber;
        this.itemName = itemName;
        this.manufacturer = manufacturer;
        this.rating = rating;
    }
    public String toString(){
        return itemName +"\t"+manufacturer+"\t\t"+serialNumber+"\t"+rating;
    }


    public static Item[] getItemByManufacturer(Item[] items, String manufacturer){

        boolean found = false;
        for(int i =0; i< items.length;i++){
            if( items[i].manufacturer == manufacturer){
                found = true;
                return items;
            }
        
            }
            if(found){
                System.out.println("Invalid Input");
            }
                return null;
            }

public class Driver{
    
    public static void main(String[] args){
        
        Item[] item = new Item[5];
        item[0] = new Item("Watch","Dorond",23945357,6.5);
        item[1] = new Item("Sunglass","Niko",13945357,6.5);
        item[2] = new Item("Blender","Decker",33945357,6.5);
        item[3] = new Item("Bottle","Decker",43945357,6.5);
        item[4] = new Item("Bag","WTravel",53965307,6.5);
        
    
   **System.out.println((Item.getItemByManufacturer(item,"Decker")));**
       
       
       
      
        
       }

}

Answer 1

这是因为数组不必使用toString方法，所以在打印它们时可以得到hashcode。打印它们的一种方法是只使用内部java库数组。toString：

System.out.println(Arrays.toString(Item.getItemByManufacturer(item,"Decker"));

或者通过将数组转换为带有数组的列表。asList：

System.out.println(Arrays.asList(Item.getItemByManufacturer(item,"Decker"));