Listview行在android的listview滚动中随机改变顺序

Question

我有一个ListView和一个BaseAdapter.我正在从webservice下载产品并在listview上显示.它在listview上正确显示.

但是当我滚动ListView时,显示随机位置的行意味着有时第三行显示在第一个位置,中间位置行显示在最后位置,依此类推.

这是我的适配器类

public class ProductListAdapter extends BaseAdapter implements OnClickListener{

    LayoutInflater inflater;
    ArrayList<Product> arrProducts;
    Context c;

    public ProductListAdapter(Context c, ArrayList<Product> arrProducts) {
        super();
        inflater = LayoutInflater.from(c);
        this.arrProducts = arrProducts;
        this.c = c;
    }

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

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

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

    @Override
    public View getView(int position, View v, ViewGroup parent) {
        Product product = null;
        if(v == null) {
            v = inflater.inflate(R.layout.product_listview_row, null);
            product = (Product) getItem(position);
            v.setTag(product);
        }else {
            product = (Product)v.getTag();
        }

        v.setOnClickListener(this);

        TextView tvProductname = (TextView)v.findViewById(R.id.tvProductname);
        tvProductname.setText(product.getTitle());

        String strReviewCount = product.getReviews();
        TextView tvReviewsCounts = (TextView)v.findViewById(R.id.tvReviews);
        if(strReviewCount != null) tvReviewsCounts.setText(strReviewCount +" Reviews");

        Button btnPrice = (Button)v.findViewById(R.id.btnPrice);
        btnPrice.setText(product.getSellingPrice());

        return v;
    }

    @Override
    public void onClick(View v) {
        Product product = (Product) v.getTag();
        Intent i = new Intent(c, ProductDetails.class);
        i.putExtra(Product.PROD_ID, product.getId());
        startActivity(i);
    }

    @Override
    public int getItemViewType(int position) {
        return super.getItemViewType(position);
    }

    @Override
    public int getViewTypeCount() {
        return super.getViewTypeCount();
    }
}

这是XML布局上的ListView

<ListView android:id="@+id/lstProducts" style="@style/fill_parent"
        android:dividerHeight="1dp" android:divider="#dbd3c5"
        android:scrollbars="vertical" android:layout_below="@id/layLine"></ListView>

此外,当我getView()像这样更改BaseAdapter的方法时,它工作正常

@Override
    public View getView(int position, View v, ViewGroup parent) {
        Product product = null;
        v = inflater.inflate(R.layout.product_listview_row, null);
        product = (Product) getItem(position);
        v.setTag(product);
        v.setOnClickListener(this);

        TextView tvProductname = (TextView)v.findViewById(R.id.tvProductname);
        tvProductname.setText(product.getTitle());

        String strReviewCount = product.getReviews();
        TextView tvReviewsCounts = (TextView)v.findViewById(R.id.tvReviews);
        if(strReviewCount != null) tvReviewsCounts.setText(strReviewCount +" Reviews");

        Button btnPrice = (Button)v.findViewById(R.id.btnPrice);
        btnPrice.setText(product.getSellingPrice());

        return v;
    }

但是这种类型的问题是我在listview行上显示产品的图像,这里我没有考虑过.使用这种类型的代码getView()方法总是在滚动listView时创建新的View,这样我就不得不一次又一次地下载图像.I使用的ImageLoader类cash memory用于下载图像,但问题是,当我将图像设置为ImageView很多次它给我out of memory error.

请帮我解决这个问题.

谢谢

Answer 1

由于链接到正确的解决方案,我来到这里.

这里的问题是您在创建新视图时将产品绑定到视图一次.您应该在每次通话时拨打以下电话getView:

product = (Product) getItem(position);
v.setTag(product);

但是你可以v.setOnClickListener(this)在创建视图后调用它(无论如何它都不会改变).

这应该可以解决问题.这里只是滥用了视图类型实现.我建议在这里阅读我的答案 ......

Answer 2

因此,根据Knickedi提出的建议,该方法应如下所示:getView()

public View getView(int position, View v, ViewGroup parent) {

    TextView tvProductname;
    TextView tvReviewsCounts;
    Button btnPrice;

    // Phase 1...
    if (v == null) {
        v = inflater.inflate(R.layout.product_listview_row, null);
        v.setOnClickListener(this);

        tvProductname = (TextView)v.findViewById(R.id.tvProductname);
        tvReviewsCounts = (TextView)v.findViewById(R.id.tvReviews);
        btnPrice = (Button)v.findViewById(R.id.btnPrice);

        v.setTag(R.id.tvProductname, tvProductname);
        v.setTag(R.id.tvReviews, tvReviewsCounts);
        v.setTag(R.id.btnPrice, btnPrice);
    }
    else {
        tvProductname = (TextView) v.getTag(R.id.tvProductname);
        tvReviewsCounts = (TextView) v.getTag(R.id.tvReviews);
        btnPrice = (Button) v.getTag(R.id.btnPrice);   
    }

    // Phase 2...
    Product product = (Product) getItem(position);

    tvProductname.setText(product.getTitle());
    btnPrice.setText(product.getSellingPrice());

    String strReviewCount = product.getReviews();
    if(strReviewCount != null)
        tvReviewsCounts.setText(strReviewCount +" Reviews");

    return v;
}