当调用方法时，java ArrayList始终为空

Question

我的程序很简单。我有一个有2个方法的类。我有另一个类在那里调用这两个方法。当调用第一个方法时，初始化arraylist并填充一些对象，然后调用第二个方法，简单地告诉arraylist的大小并打印出来。我不明白为什么我总是得到一个空的时候，第二个方法被调用。然而，当我在第一个方法中打印数组时，我得到了大小和所有it元素。Arraylist是公共得..请看一下代码。

在第一班

Items initialize = new Items();
initialize.init(); 
Items view = new Items();
view.viewItems();

public class Items {

public String id;
public String name;
public String details;
public String stock;

public ArrayList<Items> myList = new ArrayList<Items>();

public void init(){

    Items item1 = new Items();


item1.id = "0023";
item1.name = "Round Table";
item1.details = "Brown, high quality wood blah blah..";
item1.stock = "34";
myList.add(item1);


if(myList.size()==0){
        System.out.println("There are no products to display");
    }

    Iterator<Items> iterator = myList.iterator();
    System.out.println(myList.size());
            System.out.println("Products Available:");
    while(iterator.hasNext()){
        Items current = iterator.next();

        System.out.println("\nID: " +current.id + "\nTitle: "+current.name+"\nDescreption: "+current.details+"\nAmount: "+current.stock);

}

public void viewItems() {

int size  = myList.size();

if(myList.size()==0){
        System.out.println("There are no products to display");
    }

    Iterator<Items> iterator = myList.iterator();
    System.out.println(myList.size());
            System.out.println("Products Available:");
    while(iterator.hasNext()){
        Items current = iterator.next();

        System.out.println("\nID: " +current.id + "\nTitle: "+current.name+"\nDescreption: "+current.details+"\nAmount: "+current.stock);



}

Answer 1

您正在创建项的新实例然后调用viewItems()方法。您必须在调用init()的同一实例上调用viewItems（

Items initialize = new Items();
initialize.init(); 
initialize .viewItems();