How to list all the PDF files from a selected folder in Android App? – API 35 | Android 15

List PDFs from selected folder in Android App

In this video it shows the Android app code to list all the PDF files from a folder picked by the user in Android App.

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Details:

package com.programmerworld.pdfreader;

import android.content.Intent;
import android.database.Cursor;
import android.net.Uri;
import android.os.Bundle;
import android.provider.DocumentsContract;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.ListView;
import android.widget.Toast;

import androidx.activity.result.ActivityResultLauncher;
import androidx.activity.result.contract.ActivityResultContracts;
import androidx.appcompat.app.AppCompatActivity;

import java.util.ArrayList;

public class MainActivity extends AppCompatActivity {
    private ListView listView;
    private ArrayList<String> pdfFilesList;
    private ArrayAdapter<String> adapter;

    // Launcher for SAF to pick the Downloads directory
    private final ActivityResultLauncher<Intent> directoryPickerLauncher =
            registerForActivityResult(new ActivityResultContracts.StartActivityForResult(), result -> {
                if ((result.getResultCode() == RESULT_OK) && (result.getData() != null)) {
                    Uri treeUri = result.getData().getData();
                    if (treeUri != null) {
                        // Persist the permission across restarts
                        getContentResolver().takePersistableUriPermission(
                                treeUri,
                                Intent.FLAG_GRANT_READ_URI_PERMISSION
                        );
                        listPdfFiles(treeUri);
                    }
                } else {
                    Toast.makeText(this, "No directory selected", Toast.LENGTH_SHORT).show();
                }
            });

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

        listView = findViewById(R.id.listView);
        Button btnListPdfs = findViewById(R.id.btnListPdfs);
        pdfFilesList = new ArrayList<>();
        adapter = new ArrayAdapter<>(this, android.R.layout.simple_list_item_1, pdfFilesList);
        listView.setAdapter(adapter);

        btnListPdfs.setOnClickListener(v -> openDownloadsDirectoryPicker());
    }

    private void openDownloadsDirectoryPicker() {
        Intent intent = new Intent(Intent.ACTION_OPEN_DOCUMENT_TREE);
        // Optionally, suggest the Downloads directory (not guaranteed to work on all devices)
        intent.putExtra(DocumentsContract.EXTRA_INITIAL_URI,
                Uri.parse("content://com.android.externalstorage.documents/document/primary:Download"));
        directoryPickerLauncher.launch(intent);
    }

    private void listPdfFiles(Uri treeUri) {
        pdfFilesList.clear();
        try {
            // Query the document tree
            Uri childrenUri = DocumentsContract.buildChildDocumentsUriUsingTree(
                    treeUri,
                    DocumentsContract.getTreeDocumentId(treeUri)
            );

            Cursor cursor = getContentResolver().query(
                    childrenUri,
                    new String[]{
                            DocumentsContract.Document.COLUMN_DISPLAY_NAME,
                            DocumentsContract.Document.COLUMN_MIME_TYPE
                    },
                    null,
                    null,
                    null
            );

            if (cursor != null) {
                while (cursor.moveToNext()) {
                    String fileName = cursor.getString(0); // COLUMN_DISPLAY_NAME
                    String mimeType = cursor.getString(1); // COLUMN_MIME_TYPE
                    if ("application/pdf".equals(mimeType)) {
                        pdfFilesList.add(fileName);
                    }
                }
                cursor.close();
            }

            if (pdfFilesList.isEmpty()) {
                Toast.makeText(this, "No PDF files found", Toast.LENGTH_SHORT).show();
            } else {
                Toast.makeText(this, "Found " + pdfFilesList.size() + " PDF files", Toast.LENGTH_SHORT).show();
            }
        } catch (Exception e) {
            Toast.makeText(this, "Error: " + e.getMessage(), Toast.LENGTH_LONG).show();
        }
        adapter.notifyDataSetChanged();
    }
}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:padding="16dp">

    <Button
        android:id="@+id/btnListPdfs"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="100dp"
        android:text="List PDF Files from Downloads" />

    <ListView
        android:id="@+id/listView"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

</LinearLayout>

No changes required in Manifest File:

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools">

    <application
        android:allowBackup="true"
        android:dataExtractionRules="@xml/data_extraction_rules"
        android:fullBackupContent="@xml/backup_rules"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/Theme.PDFReader"
        tools:targetApi="31">
        <activity
            android:name=".MainActivity"
            android:exported="true">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

Screenshots: