如何在android中的自定义适配器之间进行正确的交互？

Question

我写了一个关于购物的简单测试代码。和图片一样add from right to left

这很简单。 ListViews 显示“项目”。 “项目”只有名称和数量。在右侧，我更改计数并将商品添加到左侧的购物车中。

重点在这里，当我更改之前添加的商品数量并再次将商品添加到购物车时，购物车和菜单中的所有相同商品都会更改为最后一个计数。

在我拍完第一张照片后，我更改了相同项目的计数并再次添加。因此，购物车中的两件商品的最后计数相同。我无法理解代码中的错误。 Second screenshot after added the same item with different count

提前致谢。

我发现了一些关于代码的东西。所有的 ArrayList 都表现得像静态的一样。如果我将菜单中添加按钮的 onClick 更改为：

ImageButton ekle = (ImageButton) view.findViewById(R.id.imageButton2);
ekle.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View v) {
        //After changing this row, all the ArrayList's (menu and cart) items 
        //in this position is changing to the same number 5.
        //And I delete the EditText's TextChangeListener, as well.
        menu.get(position).setCount(5);
        ((BaseAdapter) context.list1.getAdapter()).notifyDataSetChanged();
    }
});

---

public class Item {
    private String name;
    private int count;

    public Item(String s, int i) {
        name = s;
        count = i;
    }

    public String getName() {return name;}
    public int getCount() {return count;}
    public void setName(String s) {name = s;}
    public void setCount(int i) {count = i;}
}

---

public class MainActivity extends AppCompatActivity {
ListView list1;
ListView list2;
static ArrayList<Item> menu = new ArrayList<>();
static ArrayList<Item> cart = new ArrayList<>();
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    menu.add(new Item("Item1", 1));
    menu.add(new Item("Item2", 1));
    menu.add(new Item("Item3", 1));
    menu.add(new Item("Item4", 1));
    menu.add(new Item("Item5", 1));

    list1 = (ListView) findViewById(R.id.list1);
    list1.setAdapter(new CartAdapter(this, cart));
    list2 = (ListView) findViewById(R.id.list2);
    list2.setAdapter(new MenuAdapter(this, menu));
}
}

---

public class CartAdapter extends BaseAdapter {
MainActivity context;
ArrayList<Item> cart;

public CartAdapter(Activity activity, ArrayList<Item> m) {
    context = (MainActivity) activity;
    cart = m;
}

@Override
public int getCount() {
    return cart.size();
}

@Override
public Object getItem(int position) {
    return cart.get(position);
}

@Override
public long getItemId(int position) {
    return position;
}

@Override
public View getView(int position, View convertView, ViewGroup parent) {
    View view;
    LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    view = inflater.inflate(R.layout.item_list, null);

    TextView name = (TextView) view.findViewById(R.id.textView);
    name.setText(cart.get(position).getName());

    EditText count = (EditText) view.findViewById(R.id.editText);
    count.setText("" + cart.get(position).getCount());
    return view;
}
}

---

public class MenuAdapter extends BaseAdapter {
MainActivity context;
ArrayList<Item> menu;

public MenuAdapter(Activity activity, ArrayList<Item> m) {
    context = (MainActivity) activity;
    menu = m;
}

@Override
public int getCount() {
    return menu.size();
}

@Override
public Object getItem(int position) {
    return menu.get(position);
}

@Override
public long getItemId(int position) {
    return position;
}

@Override
public View getView(final int position, View convertView, ViewGroup parent) {
    View view;
    LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    view = inflater.inflate(R.layout.item_list2, null);

    ImageButton ekle = (ImageButton) view.findViewById(R.id.imageButton2);
    ekle.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            MainActivity.cart.add(menu.get(position));
            ((BaseAdapter) context.list1.getAdapter()).notifyDataSetChanged();
        }
    });

    TextView name = (TextView) view.findViewById(R.id.textView2);
    name.setText(menu.get(position).getName());

    EditText miktar = (EditText) view.findViewById(R.id.editText2);
    miktar.addTextChangedListener(new TextWatcher() {
        @Override
        public void beforeTextChanged(CharSequence s, int start, int count, int after) {

        }

        @Override
        public void onTextChanged(CharSequence s, int start, int before, int count) {
            if (count != 0) {
                int i = Integer.parseInt(s.toString());
                Item item = menu.get(position);
                item.setCount(i);
                MainActivity.menu.set(position, item);

                CharSequence text = menu.get(position).getName() +" : "+ menu.get(position).getCount();
                int duration = Toast.LENGTH_SHORT;
                Toast toast = Toast.makeText(context, text, duration);
                toast.show();
            }
        }

        @Override
        public void afterTextChanged(Editable s) {

        }
    });
    return view;
}

@Override
public void notifyDataSetChanged() {
    super.notifyDataSetChanged();
}
}

Answer 1

我找到了问题的原因。这两个 ArrayList 的行为都像静态的（但它们不是！）。所以我改变了 Item 类的 decleration，使 count 成为 final。就这样，问题解决了。

public class Item 
{
private String name;
private final int count;

public Item(String s, int i) {
    name = s;
    count = i;
}

public String getName() {return name;}
public int getCount() {return count;}
public void setName(String s) {name = s;}
}