使用AndroidPdfViewer库时遇到以下错误。 这是我遇到的错误:
FATAL EXCEPTION: main
Process: app.com.application, PID: 16559
java.lang.NullPointerException: Attempt to invoke virtual method 'com.github.barteksc.pdfviewer.PDFView$Configurator com.github.barteksc.pdfviewer.PDFView.fromStream(java.io.InputStream)' on a null object reference
at app.com.application.activity.Main2Activity$RetrievePDFStream.onPostExecute(Main2Activity.java:65)
at app.com.application.activity.Main2Activity$RetrievePDFStream.onPostExecute(Main2Activity.java:38)
我的代码:
public class Main2Activity extends Activity {
String URL_PDF = "http://192.168.1.103/android_login_api/PDF/1G.pdf";
PDFView pdfView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main2);
// view pdf from url
new RetrievePDFStream().execute(URL_PDF);
}
private class RetrievePDFStream extends AsyncTask <String, Void, InputStream>{
@Override
protected InputStream doInBackground(String... strings) {
InputStream inputStream = null;
URL url = null;
try {
url = new URL(strings[0]);
} catch (MalformedURLException e) {
e.printStackTrace();
}
try {
HttpURLConnection httpURLConnection = (HttpURLConnection) url.openConnection();
if (httpURLConnection.getResponseCode()==200){
inputStream = new BufferedInputStream(httpURLConnection.getInputStream());
}
} catch (IOException e) {
return null;
}
return inputStream;
}
@Override
protected void onPostExecute(InputStream inputStream) {
pdfView.fromStream(inputStream).load();
}
}
}
请指导我解决问题,谢谢。
我还有另一个问题:是否可以使用此方法Volley
代替AsyncTask
?
答案 0 :(得分:2)
这是因为pdfView
为空。