AsyncTask 和 JSOUP 解析

Question

所以基本上我试图使用 AsyncTask 解析来自网站的一些数据，我希望它从程序中获取网站 url，用下载的数据更新 ui 并显示 progressdialog（旋转轮）所以我想我需要这样做：（更新）：k 现在可以使用变量，但程序强制关闭

private class backgroundDATA extends AsyncTask<String, Void, Void> {

    ProgressDialog dialog;
    Document doc;

    @Override
    protected void onPreExecute() {

        dialog = dialog.show(Result.this, " ",
                " Loading. Please wait ... ", true);
    }

    @Override
    protected Void doInBackground(String... params) {

        try {

            doc = Jsoup.connect(params[0]).get();


        } catch (IOException e){
            e.printStackTrace();
        }   

        return null;
    }




protected void onPostExecute(Void result) {


        Elements maine;
        Elements titleJSOUP;
        Elements recipeJSOUP;
        Elements instructionsJSOUP;

        String recipE;

        maine = doc.select("div#recipeContent");

        titleJSOUP = doc.select("title");

        recipeJSOUP = maine.select("ul.recipe");

        instructionsJSOUP = maine.select("p.instructions");



        recipE = recipeJSOUP.toString();


        drinkNameText.setText("THE "
                + Jsoup.parse(titleJSOUP.toString()).text()
                        );



        dontListenText.setText(Jsoup.parse(titleJSOUP.toString()).text()
                        );

        recipeText.setText(prepareDRINK(recipE));

        instructionsText.setText(Jsoup.parse(instructionsJSOUP.toString())
                .text());

        dialog.dismiss();


    }

}

Answer 1

这将导致NullPointerException 开始......

@Override
protected void onPreExecute() {

    dialog = dialog.show(Result.this, " ",
            " Loading. Please wait ... ", true);
}

您不能调用dialog.show(...)，因为dialog 将是null。

改为调用静态ProgressDialog.show(...) 方法。