java - 尝试在空对象引用上调用虚拟方法 'java.lang.String org.jsoup.nodes.Element.ownText()'

Question

我正在使用下面的代码通过使用 jsoup 从 playstore 获取 versionName 我正在获取详细信息但它抛出一些异常。

我的代码是

public class ForceUpdateAsync extends AsyncTask<String, String, JSONObject>{

private String latestVersion;
private String currentVersion;
private Context context;
public ForceUpdateAsync(String currentVersion, Context context){
    this.currentVersion = currentVersion;
    this.context = context;
}

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

    try {
         latestVersion = Jsoup.connect("https://play.google.com/store/apps/details?id="+context.getPackageName()+"&hl=en")
                .timeout(30000)
                .userAgent("Mozilla/5.0 (Windows; U; WindowsNT 5.1; en-US; rv1.8.1.6) Gecko/20070725 Firefox/2.0.0.6")
                .referrer("http://www.google.com")
                .get()
                .select("div[itemprop=softwareVersion]")
                .first()
                 .ownText();

    } catch (IOException e) {
        e.printStackTrace();
    }
    return new JSONObject();
}

@Override
protected void onPostExecute(JSONObject jsonObject) {
    if(latestVersion!=null){
        if(!currentVersion.equalsIgnoreCase(latestVersion)){
           // Toast.makeText(context,"update is available.",Toast.LENGTH_LONG).show();
            if(!(context instanceof SplashActivity)) {
                if(!((Activity)context).isFinishing()){
                    showForceUpdateDialog();
                }
            }
        }
    }
    super.onPostExecute(jsonObject);
}

public void showForceUpdateDialog(){
    AlertDialog.Builder alertDialogBuilder = new AlertDialog.Builder(new ContextThemeWrapper(context,
            R.style.DialogDark));

    alertDialogBuilder.setTitle(context.getString(R.string.youAreNotUpdatedTitle));
    alertDialogBuilder.setMessage(context.getString(R.string.youAreNotUpdatedMessage) + " " + latestVersion + context.getString(R.string.youAreNotUpdatedMessage1));
    alertDialogBuilder.setCancelable(false);
    alertDialogBuilder.setPositiveButton(R.string.update, new DialogInterface.OnClickListener() {
        public void onClick(DialogInterface dialog, int id) {
            context.startActivity(new Intent(Intent.ACTION_VIEW, Uri.parse("market://details?id=" + context.getPackageName())));
            dialog.cancel();
        }
    });
    alertDialogBuilder.show();
}
}

但是我得到空指针异常错误

FATAL EXCEPTION: AsyncTask #1 Process: com.yabeee.yabeee, PID: 15893 java.lang.RuntimeException: An error occured while executing doInBackground() at android.os.AsyncTask$3.done(AsyncTask.java:304) at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:355) at java.util.concurrent.FutureTask.setException(FutureTask.java:222) at java.util.concurrent.FutureTask.run(FutureTask.java:242) at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587) at java.lang.Thread.run(Thread.java:818) Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String org.jsoup.nodes.Element.ownText()' on a null object reference at com.yabeee.yabeee.ModelClasses.ForceUpdateAsync.doInBackground(ForceUpdateAsync.java:53) at com.yabeee.yabeee.ModelClasses.ForceUpdateAsync.doInBackground(ForceUpdateAsync.java:28) at android.os.AsyncTask$2.call(AsyncTask.java:292) at java.util.concurrent.FutureTask.run(FutureTask.java:237) at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231)  at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)  at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)  at java.lang.Thread.run(Thread.java:818)

请有人帮我解决这个问题。

Answer 1

更新后的代码:

 newVersion = Jsoup.connect("https://play.google.com/store/apps/details?id=" + mCom.getPackageName()+ "&hl=en")
                            .timeout(30000)
                            .userAgent("Mozilla/5.0 (Windows; U; WindowsNT 5.1; en-US; rv1.8.1.6) Gecko/20070725 Firefox/2.0.0.6")
                            .referrer("http://www.google.com")
                            .get()
                            .select("div.hAyfc:nth-child(4) > span:nth-child(2) > div:nth-child(1) > span:nth-child(1)")
                            .first()
                            .ownText();