[stable-34.1.x] fix(upload): prevent crash from duplicate stable IDs in local file list

app/src/main/java/com/owncloud/android/ui/adapter/LocalFileListAdapter.java

@@ -78,6 +78,9 @@ public class LocalFileListAdapter extends RecyclerView.Adapter<RecyclerView.View
     private static final int PAGE_SIZE = 50;
     private int currentOffset = 0;
 
+    private static final long HEADER_ID = Long.MIN_VALUE;
+    private static final long FOOTER_ID = Long.MIN_VALUE + 1;
+
     public LocalFileListAdapter(boolean localFolderPickerMode,
                                 LocalFileListFragmentInterface localFileListFragmentInterface,
                                 AppPreferences preferences,
@@ -153,12 +156,22 @@ public int getItemCount() {
 
     @Override
     public long getItemId(int position) {
-        if (position >= mFiles.size()) {
-            return RecyclerView.NO_ID;
+        int headerOffset = shouldShowHeader() ? 1 : 0;
+        return getStableItemId(position, headerOffset, mFiles);
+    }
+
+    @VisibleForTesting
+    static long getStableItemId(int position, int headerOffset, List<File> files) {
+        if (headerOffset == 1 && position == 0) {
+            return HEADER_ID;
+        }
+
+        int fileIndex = position - headerOffset;
+        if (fileIndex < 0 || fileIndex >= files.size()) {
+            return FOOTER_ID;
         }
 
-        File file = mFiles.get(position);
-        return file.getAbsolutePath().hashCode();
+        return files.get(fileIndex).getAbsolutePath().hashCode();
     }
 
     @Override

app/src/test/java/com/owncloud/android/ui/adapter/LocalFileListAdapterTest.kt

@@ -0,0 +1,49 @@
+/*
+ * Nextcloud - Android Client
+ *
+ * SPDX-FileCopyrightText: 2026 Alper Ozturk <alper.ozturk@nextcloud.com>
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+package com.owncloud.android.ui.adapter
+
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertTrue
+import org.junit.Test
+import java.io.File
+
+class LocalFileListAdapterTest {
+
+    private fun sampleFiles(): List<File> = listOf(File("/sdcard/a.jpg"), File("/sdcard/b.png"), File("/sdcard/c.mp4"))
+
+    private fun assertAllPositionsHaveUniqueIds(headerOffset: Int, files: List<File>) {
+        val itemCount = files.size + 1 + headerOffset
+
+        val ids = mutableSetOf<Long>()
+        for (position in 0 until itemCount) {
+            val id = LocalFileListAdapter.getStableItemId(position, headerOffset, files)
+            assertTrue("Duplicate stable ID $id at position $position", ids.add(id))
+        }
+        assertEquals("Every position must produce a distinct stable ID", itemCount, ids.size)
+    }
+
+    @Test
+    fun stableIdsAreUniqueWhenHeaderIsVisible() {
+        assertAllPositionsHaveUniqueIds(headerOffset = 1, files = sampleFiles())
+    }
+
+    @Test
+    fun stableIdsAreUniqueWhenHeaderIsHidden() {
+        assertAllPositionsHaveUniqueIds(headerOffset = 0, files = sampleFiles())
+    }
+
+    @Test
+    fun headerAndFooterKeepDedicatedIds() {
+        val files = sampleFiles()
+
+        val headerId = LocalFileListAdapter.getStableItemId(0, 1, files)
+        val footerId = LocalFileListAdapter.getStableItemId(files.size + 1, 1, files)
+
+        assertEquals(Long.MIN_VALUE, headerId)
+        assertEquals(Long.MIN_VALUE + 1, footerId)
+    }
+}