add an activity check for the permission check

app/src/main/java/fr/free/nrw/commons/utils/DownloadUtils.kt

@@ -10,12 +10,20 @@ import fr.free.nrw.commons.Media
 import fr.free.nrw.commons.R
 import timber.log.Timber
 
+/**
+ * Utility class for managing media file downloads.
+ * This class provides a function to start downloading media files to the local SD card/storage.
+ * The downloaded file can then be opened in the Gallery or other apps.
+ */
 object DownloadUtils {
+
     /**
-     * Start the media file downloading to the local SD card/storage. The file can then be opened in
-     * Gallery or other apps.
+     * Initiates the downloading of a media file to the device's external storage.
+     * This method will check for storage permissions before attempting to download the file.
+     * If permissions are granted, the file will be saved to the device's Downloads folder.
      *
-     * @param m Media file to download
+     * @param activity Activity context to perform permission checks and display messages
+     * @param m Media object representing the file to download
      */
     @JvmStatic
     fun downloadMedia(
@@ -25,13 +33,17 @@ object DownloadUtils {
         val imageUrl = m.imageUrl
         var fileName = m.filename
         if (imageUrl == null || fileName == null || activity == null) {
-            Timber.d("Skipping download media as either imageUrl $imageUrl or filename $fileName activity is null")
+            // Log if any required parameter is null and exit
+            Timber.d("Skipping download media as either imageUrl $imageUrl or filename $fileName or activity is null")
             return
         }
-        // Strip 'File:' from beginning of filename, we really shouldn't store it
+
+        // Strip 'File:' from beginning of filename to ensure it is stored correctly
         fileName = fileName.substringAfter("File:")
         val imageUri = Uri.parse(imageUrl)
-        val req =
+
+        // Prepare a DownloadManager.Request object with the media's URI and other configurations
+        val req = try {
             DownloadManager.Request(imageUri).apply {
                 setTitle(m.displayTitle)
                 setDescription(activity.getString(R.string.app_name))
@@ -39,29 +51,43 @@ object DownloadUtils {
                 allowScanningByMediaScanner()
                 setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED)
             }
+        } catch (e: SecurityException) {
+            // Catch SecurityException if storage permission is missing, show a message, and exit
+            Toast.makeText(activity, "存储权限被拒绝，无法下载文件", Toast.LENGTH_SHORT).show()
+            return
+        }
+
+        // Check for storage permissions and perform the download action if granted
         PermissionUtils.checkPermissionsAndPerformAction(
             activity,
-            { enqueueRequest(activity, req) },
             {
-                Toast
-                    .makeText(
-                        activity,
-                        R.string.download_failed_we_cannot_download_the_file_without_storage_permission,
-                        Toast.LENGTH_SHORT,
-                    ).show()
+                if (activity != null) enqueueRequest(activity, req) // Ensure activity is not null before proceeding
             },
-            R.string.storage_permission,
-            R.string.write_storage_permission_rationale,
-            *PermissionUtils.PERMISSIONS_STORAGE,
+            {
+                // Show a message if permissions are denied and download cannot proceed
+                Toast.makeText(
+                    activity,
+                    R.string.download_failed_we_cannot_download_the_file_without_storage_permission,
+                    Toast.LENGTH_SHORT,
+                ).show()
+            },
+            R.string.storage_permission, // Title for permission rationale
+            R.string.write_storage_permission_rationale, // Message for permission rationale
+            *PermissionUtils.PERMISSIONS_STORAGE, // Permissions to request
         )
     }
 
+    /**
+     * Enqueues the download request with the system's DownloadManager.
+     *
+     * @param activity Activity context for accessing the system's DownloadManager
+     * @param req DownloadManager.Request configured with the download details
+     */
     private fun enqueueRequest(
         activity: Activity,
         req: DownloadManager.Request,
     ) {
-        val systemService =
-            activity.getSystemService(Context.DOWNLOAD_SERVICE) as DownloadManager
+        val systemService = activity.getSystemService(Context.DOWNLOAD_SERVICE) as DownloadManager
         systemService?.enqueue(req)
     }
 }

app/src/main/java/fr/free/nrw/commons/utils/StringSortingUtils.java

@@ -50,15 +50,23 @@ public class StringSortingUtils {
      * @return Number of characters the strings differ by
      */
     private static int levenshteinDistance(String str1, String str2) {
-        if (str1.equals(str2)) return 0;
-        if (str1.length() == 0) return str2.length();
-        if (str2.length() == 0) return str1.length();
+        if (str1.equals(str2)) {
+            return 0;
+        }
+        if (str1.length() == 0) {
+            return str2.length();
+        }
+        if (str2.length() == 0) {
+            return str1.length();
+        }
 
         int[] cost = new int[str1.length() + 1];
         int[] newcost = new int[str1.length() + 1];
 
         // initial cost of skipping prefix in str1
-        for (int i = 0; i < cost.length; i++) cost[i] = i;
+        for (int i = 0; i < cost.length; i++) {
+            cost[i] = i;
+        }
 
         // transformation cost for each letter in str2
         for (int j = 1; j <= str2.length(); j++) {