How can i create a pdf view in android

问题

I have have uploaded pdf files and set it to the database Stored steps in Firebase Database and i have create a code to display in android and it works fine Displaying in listview

i have create an intent to open in a new page and view the pdf in android

public class ViewPdfFiles extends AppCompatActivity {

private PDFView pdfView;
private String url;


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_view_pdf_files);

    pdfView=(PDFView) findViewById(R.id.pdfView);


    Bundle bundle = getIntent().getExtras();
    if (bundle != null) {
        url = getIntent().getStringExtra("url");
    }
    new RetrievePDFStream().execute(url);
}


class RetrievePDFStream extends AsyncTask<String,Void, InputStream> {
    @Override
    protected InputStream doInBackground(String... strings) {
        InputStream inputStream = null;

        try{

            URL url=new URL(strings[0]);
            HttpURLConnection urlConnection=(HttpURLConnection) url.openConnection();
            if(urlConnection.getResponseCode()==200){
                inputStream=new BufferedInputStream(urlConnection.getInputStream());

            }
        }catch (IOException e){
            return null;
        }
        return inputStream;

    }

    @Override
    protected void onPostExecute(InputStream inputStream) {
        pdfView.fromStream(inputStream).load();
    }
}
}

But it was giving an error

E/PDFView: load pdf error
    java.lang.NullPointerException: Attempt to invoke virtual method 'int java.io.InputStream.read(byte[])' on a null object reference
        at com.github.barteksc.pdfviewer.util.Util.toByteArray(Util.java:36)
        at com.github.barteksc.pdfviewer.source.InputStreamSource.createDocument(InputStreamSource.java:37)
        at com.github.barteksc.pdfviewer.DecodingAsyncTask.doInBackground(DecodingAsyncTask.java:53)
        at com.github.barteksc.pdfviewer.DecodingAsyncTask.doInBackground(DecodingAsyncTask.java:25)
        at android.os.AsyncTask$2.call(AsyncTask.java:333)
        at java.util.concurrent.FutureTask.run(FutureTask.java:266)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1167)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:641)
        at java.lang.Thread.run(Thread.java:764)

what's the error and how can i resolve it

来源：https://stackoverflow.com/questions/61570965/how-can-i-create-a-pdf-view-in-android

标签

java

android

firebase

firebase-realtime-database

pdfview