创建包含 ArrayLists 作为参数的对象的 ArrayList - 我的代码似乎没有创建单独的 ArrayLists？

Question

我在使用基于文本的游戏的代码时遇到问题。我的类 Locations 旨在从“配置”文本文件加载参数以创建对象。 我目前的做法是：

• 我创建了一个带有构造函数的公共类，该构造函数将获取对象（位置）的参数。它将它们作为 this.xxx 分配给私有变量。
• 我还创建了一个解析文件的公共静态类，一旦它有必要数量的参数来创建一个对象，它就会通过将它们传递给构造函数来创建一个。接下来，它将该对象添加到 ArrayList 位置列表。生成所有位置对象后，该类返回 ArrayList locations_list

我的静态类解析文本文件OK。但是，当我运行一个遍历 locations_list 并为每个元素调用 getter 的测试时，对象的 ArrayList 参数不是个性化的。所有 ArrayList 元素都返回相同的位置字符。

所有对象的 location_characters 将具有相同的内容，这是一个包含所有位置的“字符”的列表。
例如，如果位置 1 有字符 2 和 3，位置 2 有 6 和 7，我的 location_characters 将打印 [2,3,6,7]。
如果我放一个 location_characters.clear();添加到 location_list 后，所有对象的 location_characters 都为空。

示例代码sn-ps：

带有构造函数的公共类：

public class Locations {
    private final int location_id;
    private final String location_name;
    private final String location_description;
    private ArrayList <Integer> location_characters;
    private ArrayList <Integer> location_items;
    private final ArrayList <Integer> location_enter_from;
    private final ArrayList <Integer> location_exit_to;
    private String location_stage_name;
    private final int location_stages;
    private final ArrayList <String> location_stage_descriptions;

    public Locations(int location_id,
                     String location_name,
                     String location_description,
                     ArrayList <Integer> location_characters,
                     ArrayList <Integer> location_items,
                     ArrayList <Integer> location_enter_from,
                     ArrayList <Integer> location_exit_to,
                     String location_stage_name,
                     int location_stages,
                     ArrayList <String> location_stage_descriptions) {

        this.location_id = location_id;
        this.location_name = location_name;
        this.location_description = location_description;
        this.location_characters = location_characters;
        this.location_items = location_items;
        this.location_enter_from = location_enter_from;
        this.location_exit_to = location_exit_to;
        this.location_stages = location_stages;
        this.location_stage_descriptions = location_stage_descriptions;
    }

... below are getters/setters....

加载器的公共静态类：

public static ArrayList <Locations> load_locations() {
        //These are used for parsing the text file
        String line;
        ArrayList <String> lines = new ArrayList<>();

        //These are used to initialize local variables
        int location_id = 0;
        String location_name = null;
        String location_description = null;
        ArrayList<Integer> location_characters = new ArrayList<>();
        ArrayList<Integer> location_items = new ArrayList<>();
        ArrayList<Integer> location_enter_from = new ArrayList<>();
        ArrayList<Integer> location_exit_to = new ArrayList<>();
        String location_stage_name = null;
        int location_stages = 0;
        ArrayList<String> location_stage_descriptions = new ArrayList<>();
        
        //This is used to initialize ArrayList of objects
        ArrayList <Locations> location_list = new ArrayList<>();

//here goes the code for parsing the text files....
//below is a sample portion that loads i.e 2,3,4 split into ints,
//into the ArrayList location_characters....

 case "location_characters":
                            String[] characters = values[1].split(",");
                            for (String character : characters) {
                                location_characters.add(Integer.parseInt(character));
                            }
                            i++;
                            break;

//continued...

//below I am passing the parameters into constructor,
//then adding the object to ArrayList location_list
}
                    Locations location = new Locations(location_id,
                                          location_name,
                                          location_description,
                                          location_characters,
                                          location_items,
                                          location_enter_from,
                                          location_exit_to,
                                          location_stage_name,
                                          location_stages,
                                          location_stage_descriptions);
                    location_list.add(location);
                    i = 0;
                }
            }
            reader.close();
        }
        catch (IOException e){
            System.out.println("Problem reading file.");
        }
        return location_list;
    }

我会欣赏洞察力和解决方案的指针

Answer 1

您的代码不完整，问题出在您未显示的代码中：您将相同的列表传递给所有构造函数调用，因此所有位置对象对其字段使用相同的列表。

这可以通过在声明中初始化 Locations 字段来解决，例如：

private List<Integer> location_characters = new ArrayList<>();
// repeat this pattern for all List fields

并且不通过构造函数传递它们的列表。

如果需要添加到列表中：

locationsInstance.getlocation_characters().add(foo);