java - 由于在 TextView 中设置值而导致您自己的 ListView 出现问题

Question

按下按钮后，我转到 SecondActivity，输入数据，然后按下按钮后返回到 MainActivity。我在 onActivityResult 方法中创建一个对象，然后将其分配给对象数组。我将带有对象的数组发送到适配器。不幸的是，当我尝试启用该应用程序时，我收到消息:“应用程序已停止”。

我没有收到任何与错误相关的消息，但我注意到应用程序由于这些代码行而无法工作。因为当我删除它们时，应用程序会打开，我可以在这些代码行中更改什么？:

 holder.nameProduct.setText(object.name); //THIS LINE ???
 holder.priceProduct.setText(String.valueOf(object.price));//THIS LINE ???

下面我附上完整代码:

主要 Activity :

public class MainActivity extends AppCompatActivity {

    ListView listView;
    Button button_secondActivity;
    TextView textView_totalPrice;
    private static final int REQUEST_CODE = 1;
    static int indexArray = 0;

    Item items [] = new Item[10];

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        button_secondActivity = findViewById(R.id.button);
        textView_totalPrice = findViewById(R.id.textView);
        listView = findViewById(R.id.itemsList);

        button_secondActivity.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {

                Intent i = new Intent(MainActivity.this, SecondActivity.class);
                startActivityForResult(i, REQUEST_CODE);
            }
        });




        RowAdapter adapter = new RowAdapter(this, R.layout.row_element, items);
        listView.setAdapter(adapter);

    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent i) {
        if ((requestCode == REQUEST_CODE) && (resultCode == RESULT_OK)) {

            String nameProduct = i.getStringExtra("nameProduct");
            int priceProduct = i.getIntExtra("priceProduct", 0);

            Item item = new Item(priceProduct, nameProduct);

            items[indexArray] = item;

            indexArray++;
        }
    }
}

第二个 Activity :

public class SecondActivity extends AppCompatActivity {

    EditText editText_priceProduct, editText_nameProduct;
    Button button_enterData;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_second);

        editText_priceProduct = findViewById(R.id.editText);
        editText_nameProduct = findViewById(R.id.editText2);
        button_enterData = findViewById(R.id.button2);

        button_enterData.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {

                finish();
            }
        });
    }

     public void finish() {

        String nameProduct;
        int priceProduct;

        nameProduct = editText_nameProduct.getText().toString();
        priceProduct = Integer.parseInt(editText_priceProduct.getText().toString());

        Intent i = new Intent(SecondActivity.this, MainActivity.class);
        i.putExtra("nameProduct", nameProduct);
        i.putExtra("priceProduct", priceProduct);

        setResult(RESULT_OK, i);
        super.finish();

     }
}

适配器:

public class RowAdapter extends ArrayAdapter<Item> {

    Context context;
    int layoutResourceId;
    Item items[] = null;

    public RowAdapter(Context context, int layoutResourceId, Item items []) {
        super(context, layoutResourceId, items);

        this.context = context;
        this.layoutResourceId = layoutResourceId;
        this.items = items;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {

        View view = convertView;
        ItemsHolder holder = null;

        if(view == null) {

            LayoutInflater inflater = ((Activity)context).getLayoutInflater();
            view = inflater.inflate(layoutResourceId, parent, false);

            holder = new ItemsHolder();
            holder.nameProduct =  view.findViewById(R.id.textView3);
            holder.priceProduct = view.findViewById(R.id.textView2);

            view.setTag(holder);
        }

        else {

            holder = (ItemsHolder) view.getTag();
        }

        Item object = items[position];
        holder.nameProduct.setText(object.name); //THIS LINE ???
        holder.priceProduct.setText(String.valueOf(object.price));//THIS LINE ???


        return view;
    }
}



class ItemsHolder {

    TextView nameProduct, priceProduct;
}

项目:

public class Item {

    int price;
    String name;

    public Item(int price, String name) {
        this.price = price;
        this.name = name;
    }

    public int getPrice() {
        return price;
    }

    public String getName() {
        return name;
    }
}

Answer 1

请尝试以下编辑并回复我:

@Override
public View getView(int position, View view, ViewGroup parent) {
    ItemsHolder holder;
    LayoutInflater inflater = LayoutInflater.from(context);
    view = inflater.inflate(layoutResourceId, parent, false);
    holder = new ItemsHolder();
    holder.nameProduct =  view.findViewById(R.id.textView3);
    holder.priceProduct = view.findViewById(R.id.textView2);
    Item object = items[position];
    holder.nameProduct.setText(object.getName());
    holder.priceProduct.setText(String.valueOf(object.getPrice()));
    return view;
}