android - fragment 中的自定义数组适配器

Question

我是 Andriod 的新手。我已经尝试了很多次，但很长一段时间以来一直被困在这个问题上。我有一个名为 ProductListActivity 的 Activity ，在这个 Activity 中我有一个 fragment 。现在我想显示列表，为此我创建了自己的自定义数组适配器。当我不使用 fragment 但 fragment 给我 NullPointerException 时，它工作正常。我调试我的代码。请帮帮我。谢谢你的考虑。我在这里粘贴我的代码。

Activity 类:

public class ProductListActivity extends Activity implements ProductInterface{
public static String cookie;
public static String jsonSettingsResponse;
public static String[] tids;
public static String jsonPorductsCategoryListResponseString;
public JSONArray jsonPorductsCategoryListResponseArray;
public static String vid;
public static String publicPath;
public static JSONArray productsList;
public ArrayList<String> listItems;
public String[] listProCategory;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.product_category_and_list);
    Intent intent = getIntent();
    cookie = intent.getStringExtra(BConstant.WEB_SERVICES_COOKIES);
    productsList = new JSONArray();
    FetchProductCategories products = new FetchProductCategories();
    productsList = products.fetchProducts();
    listProCategory = products.onDisplayProductList(productsList).toArray(
            new String[0]);

    Bundle bundle = new Bundle();
    bundle.putString(BConstant.WEB_SERVICES_COOKIES, cookie);
    bundle.putString(BConstant.PUBLIC_PATH, publicPath);
    bundle.putStringArray(BConstant.TAXONOMY_TID, tids);
    bundle.putStringArray(BConstant.PRODUCT_CATEGORY_NAMES, listProCategory);
    ProductCategoryFragment productCategoryFragment = new ProductCategoryFragment();
    FragmentManager manager = getFragmentManager();
    productCategoryFragment.setArguments(bundle);

}

private class FetchProductCategories {
    protected JSONArray fetchProducts(String... params) {
        jsonSettingsResponse = WebserviceBUtil
                .callWebServicesGetVocabularyList(cookie);
        vid = JSONUtil.parseJSONResponse(jsonSettingsResponse,
                BConstant.TAXONOMY_VID);
        publicPath = JSONUtil.parseJSONResponse(jsonSettingsResponse,
                BConstant.PUBLIC_PATH);
        jsonPorductsCategoryListResponseString = WebserviceBUtil
                .callWebServicesGetProductsList(cookie, vid);
        tids = ProductCategoryIds.parseJSONResponseToGetTidsOfProducts(
                jsonPorductsCategoryListResponseString,
                BConstant.TAXONOMY_TID);
        try {
            jsonPorductsCategoryListResponseArray = new JSONArray(
                    jsonPorductsCategoryListResponseString);
        } catch (JSONException e) {
            e.printStackTrace();
        }
        return jsonPorductsCategoryListResponseArray;
    }


    protected ArrayList<String> onDisplayProductList(JSONArray result) {
        listItems = new ArrayList<String>();
        for (int i = 0; i < result.length(); i++) {
            try {
                listItems
                        .add(result.getJSONObject(i)
                                .getString(BConstant.NAME_CONSTANT)
                                .toString());
            } catch (Exception ex) {
                ex.printStackTrace();
            }
        }
        return listItems;
    }
}


    @Override
    public HashMap<Integer, Bitmap> DownloadImages(HashMap<Integer, String> productCategoryImagePath) {
        HashMap<Integer, Bitmap> imgBitmap = new HashMap<Integer, Bitmap>();
        for (int pos = 0; pos < productCategoryImagePath.size(); pos++) {
            Bitmap bval = ImageDownloader
                    .getBitmapFromURL(productCategoryImagePath.get(pos));
        imgBitmap.put(pos, bval);
        }
        return imgBitmap;

}
}

fragment 类:

public class ProductCategoryFragment extends Fragment {
ProductInterface productInterface;
private static String[] tids;
private static HashMap<Integer, String> productCategoryImagePath;
private static String jsonPorductsDetailsImagePathResponse;
private static String publicPath;
private static String cookie;
public String[] listProCategory;
public  ListView listOfProductsCategory;
private static HashMap<Integer, Bitmap> imgBitmapUrls;
DisplayProductListArrayAdapter adapter;


@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {
     View fragProcatView = inflater.inflate(R.layout.product_category_list, container,
                false);
     listOfProductsCategory = (ListView) getActivity().findViewById(R.id.productCategorylistView);
    return fragProcatView;

}

@Override
public void onActivityCreated(Bundle savedInstanceState) {
    super.onActivityCreated(savedInstanceState);
    publicPath = getArguments().getString(BConstant.PUBLIC_PATH);
    cookie = getArguments().getString(BConstant.WEB_SERVICES_COOKIES);
    tids = getArguments().getStringArray(BConstant.TAXONOMY_TID);
    listProCategory = getArguments().getStringArray(
            BConstant.PRODUCT_CATEGORY_NAMES);
    Bundle b = getActivity().getIntent().getExtras();
    publicPath = b.getString(BConstant.PUBLIC_PATH);
    cookie = b.getString(BConstant.WEB_SERVICES_COOKIES);
    tids =b.getStringArray(BConstant.TAXONOMY_TID);
    listProCategory =b.getStringArray(
            BConstant.PRODUCT_CATEGORY_NAMES);
    productInterface = (ProductInterface) getActivity();
    productCategoryImagePath = new HashMap<Integer, String>();
    for (int i = 0; i < tids.length; i++) {
        jsonPorductsDetailsImagePathResponse = WebserviceBUtil
                .callWebServicesGetProductsDetails(cookie, tids[i]);
        String filename = ProductCategoryIds
                .parseJSONResponseToGetVidOfProductsFromVocabulary(
                        jsonPorductsDetailsImagePathResponse,
                        BConstant.FILE_NAME);
        String completeUrl = publicPath + filename;
        productCategoryImagePath.put(i, completeUrl);
    }
    imgBitmapUrls = productInterface
            .DownloadImages(productCategoryImagePath);
     adapter = new DisplayProductListArrayAdapter(
                getActivity(), listProCategory,
                imgBitmapUrls);
    listOfProductsCategory.setAdapter(adapter);
}


/**
 * ExtendsArrayAdapterClassToDisplayCustomListView
 */
public class DisplayProductListArrayAdapter extends ArrayAdapter<String> {

    Context context;
    HashMap<Integer, Bitmap> prodctImgs;
    String[] proCategoryNames;
    HashMap<Integer, Bitmap>biturls;
    DisplayProductListArrayAdapter(Context c,
            String[] listCategory, HashMap<Integer, Bitmap> imgUrls) {
        super(c,
                R.layout.product_category_single_layout,
                R.id.productCategoryName, listCategory);
        this.context = c;
        this.prodctImgs = imgUrls;
        this.proCategoryNames = listCategory;
        this.biturls = imgUrls;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        //LayoutInflater inflater = (LayoutInflater) context
    //          .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        LayoutInflater inflater=((Activity)context).getLayoutInflater(); 
View row = inflater.inflate(R.layout.product_category_single_layout,parent,false);
        ImageView productCategoryImage = (ImageView) row
                .findViewById(R.id.productCategoryImageId);
        Bitmap bitmap = imgBitmapUrls.get(position);
        // productCategoryImage.setFocusable(false);
        TextView productCategoryName = (TextView) row
                .findViewById(R.id.productCategoryName);
        productCategoryImage.setImageBitmap(bitmap);
        productCategoryName.setText(proCategoryNames[position]);
        return row;
    }
     }
  }

Answer 1

改变

listOfProductsCategory = (ListView) getActivity().findViewById(R.id.productCategorylistView);

到

listOfProductsCategory = (ListView) fragProcatView .findViewById(R.id.productCategorylistView);

findViewById 在当前 infalted 布局中查找具有 id 的 View 。因此，请使用 View 对象来初始化您的 ListView 。

编辑:

你做这样的事情

  static ProductCategoryFragment newInstance(int num) {
    ProductCategoryFragment f = new ProductCategoryFragment();

    // Supply num input as an argument.
    Bundle args = new Bundle();
    args.putInt("num", num);
    f.setArguments(args);

    return f;
}

然后

int value = getArguments().getInt("num");

Activity 中

 ProductCategoryFragment newFragment = ProductCategoryFragment.newInstance(10);