How to make pdf Reader Android app to take pdf from assets folder?

Question

I tried:

package com.example.dell.pdfreader;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Matrix;
import android.graphics.Rect;
import android.graphics.pdf.PdfRenderer;
import android.net.Uri;
import android.os.ParcelFileDescriptor;
import android.support.v7.app.AlertDialog;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.Toast;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

public class MainActivity extends AppCompatActivity {

    private ImageView img;
    private int currentpage = 0;
    private Button next, previous;
    File file;

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

        next = (Button) findViewById(R.id.next);
        previous = (Button) findViewById(R.id.previous);
       //  file=getFile();


        next.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                currentpage++;
                render(file);
            }
        });


        previous.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                currentpage--;
                render(file);
            }
        });
    }

    private void render(File file) {

        try {

            img = (ImageView) findViewById(R.id.image);

            int width = img.getWidth();
            int height = img.getHeight();

            Bitmap bitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_4444);





            PdfRenderer renderer = new PdfRenderer(ParcelFileDescriptor.open(file, ParcelFileDescriptor.MODE_READ_ONLY));

            if (currentpage < 0) {
                currentpage = 0;

            } else if (currentpage > renderer.getPageCount()) {


                currentpage = renderer.getPageCount() - 1;

                Matrix matrix = img.getImageMatrix();

                Rect rect = new Rect(0, 0, width, height);

                renderer.openPage(currentpage).render(bitmap, rect, matrix, PdfRenderer.Page.RENDER_MODE_FOR_DISPLAY);

                img.setImageMatrix(matrix);
                img.setImageBitmap(bitmap);
                img.invalidate();

            }


        } catch (Exception e) {

            e.printStackTrace();


        }
    }

    private File getFile() {
        File file=new File(this.getExternalFilesDir(null),"Example.pdf");;
        byte buffer[]=null;
        OutputStream output = null;


        InputStream input = null;
        try {
            input = this.getAssets().open("Example.pdf");

            buffer = new byte[input.available()];
            input.read(buffer);
            output = new FileOutputStream(file);
            output.write(buffer);
        }
        catch(FileNotFoundException e){
            e.printStackTrace();
            Toast.makeText(this,"File not Found",Toast.LENGTH_LONG).show();
            return null;
        }
        catch (IOException e) {
            e.printStackTrace();
            Toast.makeText(this,"Failed to open",Toast.LENGTH_LONG).show();
            return null;
        }

    return file;
    }
}

Above code generated Following Error:

> java.lang.NullPointerException: Attempt to invoke virtual method
> 'java.lang.String java.io.File.getPath()' on a null object reference
> 03-18 15:42:16.245 6826-6826/com.example.dell.pdfreader W/System.err: 
> at
> android.os.ParcelFileDescriptor.openInternal(ParcelFileDescriptor.java:269)
> 03-18 15:42:16.245 6826-6826/com.example.dell.pdfreader W/System.err: 
> at android.os.ParcelFileDescriptor.open(ParcelFileDescriptor.java:200)
> 03-18 15:42:16.246 6826-6826/com.example.dell.pdfreader W/System.err: 
> at
> com.example.dell.pdfreader.MainActivity.render(MainActivity.java:76)
> 03-18 15:42:16.246 6826-6826/com.example.dell.pdfreader W/System.err: 
> at
> com.example.dell.pdfreader.MainActivity.access$100(MainActivity.java:26)
> 03-18 15:42:16.246 6826-6826/com.example.dell.pdfreader W/System.err: 
> at
> com.example.dell.pdfreader.MainActivity$1.onClick(MainActivity.java:47)
> 03-18 15:42:16.246 6826-6826/com.example.dell.pdfreader W/System.err: 
> at android.view.View.performClick(View.java:5265) 03-18 15:42:16.246
> 6826-6826/com.example.dell.pdfreader W/System.err:     at
> android.view.View$PerformClick.run(View.java:21534) 03-18 15:42:16.246
> 6826-6826/com.example.dell.pdfreader W/System.err:     at
> android.os.Handler.handleCallback(Handler.java:815) 03-18 15:42:16.247
> 6826-6826/com.example.dell.pdfreader W/System.err:     at
> android.os.Handler.dispatchMessage(Handler.java:104) 03-18
> 15:42:16.247 6826-6826/com.example.dell.pdfreader W/System.err:     at
> android.os.Looper.loop(Looper.java:207) 03-18 15:42:16.247
> 6826-6826/com.example.dell.pdfreader W/System.err:     at
> android.app.ActivityThread.main(ActivityThread.java:5728) 03-18
> 15:42:16.247 6826-6826/com.example.dell.pdfreader W/System.err:     at
> java.lang.reflect.Method.invoke(Native Method) 03-18 15:42:16.247
> 6826-6826/com.example.dell.pdfreader W/System.err:     at
> com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:789)
> 03-18 15:42:16.247 6826-6826/com.example.dell.pdfreader W/System.err: 
> at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:679)

file==null. You never gave it a value. You never initialized it. You never assigned a File object to it. — greenapps, Mar 18 '17 at 10:43

score 2 · Answer 1 · answered Mar 18 '17 at 11:30

2

First, as noted in the comments, file is null, because you never set a value on it.

Second, for a PDF in assets, there is no file. Use openFd() on AssetManager to get an AssetFileDescriptor on the asset, then call getParcelFileDescriptor() on the AssetFileDescriptor to get the ParcelFileDescriptor.

Third, PdfRenderer does not handle arbitrary PDF files. It is there for print preview, nothing more. Most likely, you will need to use something else.

answered Mar 18 '17 at 11:30

CommonsWare

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Thanks it helps me. – Vikki Asati Mar 19 '17 at 04:46
i did as you say but it show : – Vikki Asati Mar 19 '17 at 04:50
java.io.FileNotFoundException: This file can not be opened as a file descriptor; it is probably compressed – Vikki Asati Mar 19 '17 at 04:50
1

@VikkiAsati: You will need to tell the build tools to not compress PDF files. Add `aaptOptions { noCompress 'pdf' }` to your `android` closure in your `build.gradle` file. See [this example](https://github.com/commonsguy/cwac-provider/blob/v0.5.0/demo/build.gradle#L14-L21). – CommonsWare Mar 19 '17 at 11:25

How to make pdf Reader Android app to take pdf from assets folder?

1 Answers1