Question

在我的Android应用程序的 Fragment 中，我希望在价格，公司名称，股票代码等的帮助下，将 Yahoo Finance 的简单数据显示出来 csv （以逗号分隔的值）。当我尝试在FinanceFragment中将值设置为TextView时，我将Error作为NullPointerException。任何人都可以告诉我正确的方法或修复我的代码。

感谢您的帮助！

Activity.java

        AlertDialog.Builder builder = new AlertDialog.Builder(this);

        LayoutInflater inflater = this.getLayoutInflater();
        View dialogView = inflater.inflate(R.layout.dialog_search_ticker, null);
        builder.setView(dialogView);

        final EditText input = (EditText) dialogView.findViewById(R.id.input_ticker);
        input.setInputType(InputType.TYPE_CLASS_TEXT);

        builder.setPositiveButton("SEARCH TICKER", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {
                final String SearchTicker = input.getText().toString();

                if(SearchTicker.matches("")) { //Check if EditText is empty / If empty show message
                    Toast.makeText(getApplicationContext(), "Space is empty. Please try enter again!", Toast.LENGTH_SHORT).show();
                }else{
                    if(new YahooAsyncTask().execute(SearchTicker) == null){
                        Toast.makeText(getApplicationContext(), "There is no such ticker. Please try enter again!", Toast.LENGTH_SHORT).show();
                    }else{
                        new YahooAsyncTask().execute(SearchTicker);
                    }
                }
            }
        });

private class YahooAsyncTask extends AsyncTask<String, String, Stock> {

        LinearLayout Progress = (LinearLayout) findViewById(R.id.Progress);
        LinearLayout NoInternetConnection = (LinearLayout) findViewById(R.id.NoInternetConnection);
        FrameLayout FragmentContainer = (FrameLayout) findViewById(R.id.FragmentContainer);

        @Override
        protected void onPreExecute() {
            // Sets company info invisible, and progress indicator visible
            Progress.setVisibility(View.VISIBLE);
            NoInternetConnection.setVisibility(View.INVISIBLE);
            FragmentContainer.setVisibility(View.GONE);
        }

        protected Stock doInBackground(String... ticker) {
            Stock stock = null;
            if (isNetworkAvailable()) {
                try {
                    stock = YahooFinanceInfo.getStockData(ticker[0]);
                } catch (Exception e) {
                    Log.d("YAHOO_ERROR", e.toString());
                }
            }
            return stock;
        }

        protected void onPostExecute(Stock stock) {
            Progress.setVisibility(View.GONE);
            if (stock != null) {
                // Create a new Fragment to be placed in the activity layout
                YahooFragment yahooFragment = YahooFragment.newInstance(stock);

                if (findViewById(R.id.FragmentContainer) != null) {
                    getSupportFragmentManager().beginTransaction().replace(R.id.FragmentContainer, yahooFragment).commit();
                } else {
                    getSupportFragmentManager().beginTransaction().add(R.id.FragmentContainer, yahooFragment).commit();
                }
                FragmentContainer.setVisibility(View.VISIBLE);
            } else {
                NoInternetConnection.setVisibility(View.VISIBLE);
            }
        }
    }

Answer 1

请发布错误代码以确定，但我猜这是发生在这里：

LinearLayout HeaderProgress = (LinearLayout) getView().findViewById(R.id.progress_linear_layout);
LinearLayout NoInternetConnection = (LinearLayout) getView().findViewById(R.id.NoInternetConnection);
LinearLayout FragmentContainer = (LinearLayout) getView().findViewById(R.id.fragment_container);

此代码将在您返回onCreateView（）之前执行，这意味着getView（）可能返回null。

尝试将这些属性提取到您的活动并在调用之前初始化它们

new GetKeyStatsAsyncTask().execute(ticker);

<强>更新

这就是我在评论中的意思：

public class FinanceFragment extends Fragment {

TextView tvCompany;
TextView tvCompanyTicker;
TextView tvPrice;
TextView tvPriceChange;
TextView tvPrevClose;
TextView tvOpen;
TextView tvVolume;
TextView tvAvgDailyVolume;
TextView tvDaysRange;
TextView tvYearRange;
TextView tvOneYearTarget;
TextView tvMarketCap;

Stock stock;

String ticker;

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    View view = inflater.inflate(R.layout.fragment_finance, container, false);

    tvCompany        = (TextView) view.findViewById(R.id.tvCompany);
    tvCompanyTicker  = (TextView) view.findViewById(R.id.tvCompanyTicker);
    tvPrice          = (TextView) view.findViewById(R.id.tvPrice);
    tvPriceChange    = (TextView) view.findViewById(R.id.tvPriceChange);
    tvPrevClose      = (TextView) view.findViewById(R.id.tvPrevClose);
    tvOpen           = (TextView) view.findViewById(R.id.tvOpen);
    tvAvgDailyVolume = (TextView) view.findViewById(R.id.tvAvgDailyVolume);
    tvVolume         = (TextView) view.findViewById(R.id.tvVolume);
    tvDaysRange      = (TextView) view.findViewById(R.id.tvDaysRange);
    tvYearRange      = (TextView) view.findViewById(R.id.tvYearRange);
    tvMarketCap      = (TextView) view.findViewById(R.id.tvMarketCap);
    tvOneYearTarget  = (TextView) view.findViewById(R.id.tvOneYearTarget);


    updateView();


    // When application start working, search for Google ticker by default.
    ticker = "GOOG";
    new GetKeyStatsAsyncTask().execute(ticker);

    return view;
}
private void updateView() {
    if(stock == null) {
    // Sets company name, price, etc.
        tvCompany.setText("");
        tvCompanyTicker.setText("");
        tvPrice.setText("");
        tvPriceChange.setText("");
        tvPrevClose.setText("");
        tvOpen.setText("");
        tvAvgDailyVolume.setText("");
        tvVolume.setText("");
        tvDaysRange.setText("");
        tvYearRange.setText("");
        tvMarketCap.setText("");
        tvOneYearTarget.setText("");
    } else {

    // Sets company name, price, etc.
        tvCompany.setText(stock.getName());
        tvCompanyTicker.setText(stock.getTicker());
        tvPrice.setText(stock.getPrice());
        tvPriceChange.setText(stock.getPriceChange());
        tvPrevClose.setText(stock.getPrevClose());
        tvOpen.setText(stock.getOpen());
        tvAvgDailyVolume.setText(stock.getAvgDailyVolume());
        tvVolume.setText(stock.getVolume());
        tvDaysRange.setText(stock.getDaysRange());
        tvYearRange.setText(stock.getYearRange());
        tvMarketCap.setText(stock.getMarketCap());
        tvOneYearTarget.setText(stock.getOneYearTarget());

        // If price change is positive, set TextView to green. Otherwise Red.
        if (stock.getPriceChangeDirection() >= 0)
            tvPriceChange.setTextColor( getResources().getColor(R.color.finance_green));
        else
            tvPriceChange.setTextColor( getResources().getColor(R.color.finance_red));

    }
}
...

并更改你的onPostExecute：

protected void onPostExecute(Stock stock) {
    HeaderProgress.setVisibility(View.GONE);
    if (stock != null) {
        FragmentContainer.setVisibility(View.VISIBLE);
        updateView();
    } else {
        NoInternetConnection.setVisibility(View.VISIBLE);
    }
}

我没有尝试代码，因此无法保证其有效

从Yahoo Finance获取数据并将其显示在Fragment

1 个答案: