在v-if上计算表达式时出错

Question

我需要检查Vue组件中的值是否正确。这是我的代码：

public class ProductsAdapter extends BaseAdapter {
private ImageLoadingListener animateFirstListener = new AnimateFirstDisplayListener();

private Context context;
private ArrayList<HashMap<String, String>> postItems;
public SharedPreferences settings;
public final String PREFS_NAME = "Products";

DisplayImageOptions options;
ImageLoaderConfiguration imgconfig;

private static int _counter = 0;
private String _stringVal;

public ProductsAdapter(Context context, ArrayList<HashMap<String, String>> arraylist){
    this.context = context;

    File cacheDir = StorageUtils.getCacheDirectory(context);
    options = new DisplayImageOptions.Builder()
    .showImageOnLoading(R.drawable.loading)
    .showImageForEmptyUri(R.drawable.loading)
    .showImageOnFail(R.drawable.loading)
    .cacheInMemory(true)
    .cacheOnDisk(true)
    .considerExifParams(true)
    .displayer(new SimpleBitmapDisplayer())
    .imageScaleType(ImageScaleType.EXACTLY)
    .build();

    imgconfig = new ImageLoaderConfiguration.Builder(context)
    .build();
    ImageLoader.getInstance().init(imgconfig);

    postItems = arraylist;
    settings = context.getSharedPreferences(PREFS_NAME, 0);     

}

@Override
public int getCount() {
    return postItems.size();
}
@Override
public Object getItem(int position) {       
    return postItems.get(position);
}

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

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

        if (convertView == null) {
            LayoutInflater mInflater = (LayoutInflater)
            context.getSystemService(Activity.LAYOUT_INFLATER_SERVICE);
            convertView = mInflater.inflate(R.layout.row_products, null);   
        }
        final HashMap<String, String> map = postItems.get(position);

        ImageView imgProduct = (ImageView)convertView.findViewById(R.id.proimage);
        ImageLoader.getInstance().displayImage(ConstValue.PRO_IMAGE_BIG_PATH+map.get("image"), imgProduct, options, animateFirstListener);

        TextView txtTitle = (TextView)convertView.findViewById(R.id.proTitle);
        txtTitle.setText(map.get("title"));

        TextView txtPrice = (TextView)convertView.findViewById(R.id.txtprice);
        txtPrice.setText(map.get("price"));

        TextView textDiscount = (TextView)convertView.findViewById(R.id.textDiscount);
        textDiscount.setVisibility(View.GONE);

        TextView txtDiscountFlag = (TextView)convertView.findViewById(R.id.textDiscountFlag);
        txtDiscountFlag.setVisibility(View.GONE);

        TextView textCurrency = (TextView)convertView.findViewById(R.id.textCurrency);
        textCurrency.setText(map.get("currency"));

        final TextView value = (TextView)convertView.findViewById(R.id.textView3);

        Button txtminus = (Button) convertView.findViewById(R.id.minus);

        txtminus.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

            Log.d("src", "Decreasing value...");
            _counter--;
            _stringVal = Integer.toString(_counter);
            value.setText(_stringVal);

            if (_counter < 0)
            {
                value.setText("0");
            }

        }
        });

        Button txtplus  = (Button) convertView.findViewById(R.id.plus);
        txtplus.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            Log.d("src", "Increasing value...");
            _counter++;
            _stringVal = Integer.toString(_counter);
            value.setText(_stringVal);
        }
        });


        if(!map.get("discount").equalsIgnoreCase("") && !map.get("discount").equalsIgnoreCase("0")){
            Double discount = Double.parseDouble(map.get("discount"));
            Double price = Double.parseDouble(map.get("price"));
            Double discount_amount =  discount * price / 100;

            Double effected_price = price - discount_amount ; 
            //txtPrice.setBackgroundResource(R.drawable.strike_trough);
            txtPrice.setPaintFlags(txtPrice.getPaintFlags() | Paint.STRIKE_THRU_TEXT_FLAG);
            textDiscount.setVisibility(View.VISIBLE);
            textDiscount.setText(effected_price.toString());

            txtDiscountFlag.setVisibility(View.VISIBLE);
            txtDiscountFlag.setText(discount+"% off");
        }

        TextView txtUnit = (TextView)convertView.findViewById(R.id.txtunit);
        txtUnit.setText(map.get("gmqty"));

        TextView txtgm = (TextView)convertView.findViewById(R.id.txtgm);
        txtgm.setText(map.get("unit"));

        int a = Integer.parseInt(map.get("total_qty_stock").toString());
        int b = Integer.parseInt(map.get("consume_qty_stock").toString());

        int result = a - b;

        TextView txtstock = (TextView)convertView.findViewById(R.id.stock);
        txtstock.setText(String.valueOf(result)+" "+map.get("type")+" In Stock");
        //txtstock.setText(map.get("stock")+" "+map.get("type")+" In Stock");


    return convertView;
}

}

但我收到错误： public SharedPreferences settings; public ConnectionDetector cd; static ArrayList<HashMap<String, String>> products_array; ProductsAdapter adapter; ListView products_listview; DisplayImageOptions options; ImageLoaderConfiguration imgconfig; ProgressDialog dialog; TextView txtcount; Button btn; private ImageLoadingListener animateFirstListener = new AnimateFirstDisplayListener(); HashMap<String, String> catMap; @SuppressWarnings("unchecked") @Override protected void onCreate(Bundle savedInstanceState) { settings = getSharedPreferences(ConstValue.MAIN_PREF, 0); cd = new ConnectionDetector(getApplicationContext()); super.onCreate(savedInstanceState); setContentView(R.layout.activity_products); /* ActionBar mActionBar = getActionBar(); mActionBar.setDisplayShowHomeEnabled(true); mActionBar.setDisplayShowTitleEnabled(true); LayoutInflater mInflater = LayoutInflater.from(this); View mCustomView = mInflater.inflate(R.layout.custom_actionbar, null); TextView mTitleTextView = (TextView) mCustomView.findViewById(R.id.title_text); mTitleTextView.setText("My Own Title"); mActionBar.setCustomView(mCustomView); mActionBar.setDisplayShowCustomEnabled(true); */ settings = getSharedPreferences(ConstValue.MAIN_PREF, 0); cd=new ConnectionDetector(this); File cacheDir = StorageUtils.getCacheDirectory(this); options = new DisplayImageOptions.Builder() .showImageOnLoading(R.drawable.loading) .showImageForEmptyUri(R.drawable.loading) .showImageOnFail(R.drawable.loading) .cacheInMemory(true) .cacheOnDisk(true) .considerExifParams(true) .displayer(new SimpleBitmapDisplayer()) .imageScaleType(ImageScaleType.NONE) .build(); imgconfig = new ImageLoaderConfiguration.Builder(this) .build(); ImageLoader.getInstance().init(imgconfig); ArrayList<HashMap<String,String>> categoryArray = new ArrayList<HashMap<String,String>>(); try { categoryArray = (ArrayList<HashMap<String,String>>) ObjectSerializer.deserialize(settings.getString("categoryname", ObjectSerializer.serialize(new ArrayList<HashMap<String,String>>()))); }catch (IOException e) { e.printStackTrace(); } catMap = new HashMap<String, String>(); catMap = categoryArray.get(getIntent().getExtras().getInt("position")); products_array = new ArrayList<HashMap<String,String>>(); try { products_array = (ArrayList<HashMap<String,String>>) ObjectSerializer.deserialize(settings.getString("products_"+catMap.get("id"), ObjectSerializer.serialize(new ArrayList<HashMap<String,String>>()))); }catch (IOException e) { e.printStackTrace(); } products_listview = (ListView)findViewById(R.id.listView1); adapter = new ProductsAdapter(getApplicationContext(), products_array); products_listview.setAdapter(adapter); TextView txtTitle = (TextView)findViewById(R.id.catname); txtTitle.setText(catMap.get("name")); txtcount = (TextView)findViewById(R.id.textcount); btn = (Button) findViewById(R.id.button); products_listview.setOnItemClickListener(new OnItemClickListener() { @Override public void onItemClick(AdapterView<?> arg0, View arg1, final int position, long id) { // TODO Auto-generated method stub try { settings.edit().putString("selected_product", ObjectSerializer.serialize(products_array.get(position))).commit(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } Intent intent = new Intent(ProductsActivity.this, ProductdetailActivity.class); intent.putExtra("position", position); startActivity(intent); } }); new loadProductsTask().execute(true); } @Override public boolean onCreateOptionsMenu(Menu menu) { // Inflate the menu; this adds items to the action bar if it is present. getMenuInflater().inflate(R.menu.main, menu); return true; } public class loadProductsTask extends AsyncTask<Boolean, Void, ArrayList<HashMap<String, String>>> { JSONParser jParser; JSONObject json; String count; @Override protected void onPreExecute() { // TODO Auto-generated method stub super.onPreExecute(); } @Override protected void onPostExecute(ArrayList<HashMap<String, String>> result) { // TODO Auto-generated method stub if (result!=null) { //adapter.notifyDataSetChanged(); } try { settings.edit().putString("products_"+catMap.get("id"), ObjectSerializer.serialize(products_array)).commit(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } txtcount.setText(count); adapter.notifyDataSetChanged(); super.onPostExecute(result); } @Override protected void onProgressUpdate(Void... values) { // TODO Auto-generated method stub super.onProgressUpdate(values); } @Override protected void onCancelled(ArrayList<HashMap<String, String>> result) { // TODO Auto-generated method stub super.onCancelled(result); } @Override protected ArrayList<HashMap<String, String>> doInBackground( Boolean... params) { // TODO Auto-generated method stub try { jParser = new JSONParser(); if(cd.isConnectingToInternet()) { String urlstring = ConstValue.JSON_PRODUCTS+"&id="+catMap.get("id"); json = jParser.getJSONFromUrl(urlstring); count = json.getString("count"); if (json.has("data")) { if(json.get("data") instanceof JSONArray){ JSONArray jsonDrList = json.getJSONArray("data"); products_array.clear(); for (int i = 0; i < jsonDrList.length(); i++) { JSONObject obj = jsonDrList.getJSONObject(i); put_object(obj); } }else if(json.get("data") instanceof JSONObject){ put_object(json.getJSONObject("data")); } } }else { Toast.makeText(ProductsActivity.this, "Please connect mobile with working Internet", Toast.LENGTH_LONG).show(); } jParser = null; json = null; } catch (Exception e) { // TODO: handle exception return null; } return null; } public void put_object(JSONObject obj){ HashMap<String, String> map = new HashMap<String, String>(); try { map.put("id", obj.getString("id")); map.put("title", obj.getString("title")); map.put("slug", obj.getString("slug")); map.put("description", obj.getString("description")); map.put("image", obj.getString("image")); map.put("price", obj.getString("price")); map.put("currency", obj.getString("currency")); map.put("discount", obj.getString("discount")); map.put("cod", obj.getString("cod")); map.put("emi", obj.getString("emi")); map.put("status", obj.getString("status")); map.put("gmqty", obj.getString("gmqty")); map.put("unit", obj.getString("unit")); map.put("deliverycharge", obj.getString("deliverycharge")); map.put("tax", obj.getString("tax")); map.put("category_id", obj.getString("category_id")); map.put("on_date", obj.getString("on_date")); map.put("stock", obj.getString("stock")); map.put("type", obj.getString("type")); map.put("total_qty_stock", obj.getString("total_qty_stock")); map.put("consume_qty_stock", obj.getString("consume_qty_stock")); products_array.add(map); } catch (JSONException e) { // TODO Auto-generated catch block e.printStackTrace(); } } }

我做错了什么？

Answer 1

什么是userContent？您的数据中没有。

相反，请直接检查rasters_previews_list：

v-if="rasters_previews_list.length"