fix(share): keep the common MIME type when sharing several files on Android

share/android/src/main/java/com/capacitorjs/plugins/share/SharePlugin.java

@@ -167,16 +167,14 @@ public void share(PluginCall call) {
     private void shareFiles(JSArray files, Intent intent, PluginCall call) {
         List<Object> filesList;
         ArrayList<Uri> fileUris = new ArrayList<>();
+        String sharedType = null;
         try {
             filesList = files.toList();
             for (int i = 0; i < filesList.size(); i++) {
                 String file = (String) filesList.get(i);
                 if (isFileUrl(file)) {
-                    String type = getMimeType(file);
-                    if (type == null || filesList.size() > 1) {
-                        type = "*/*";
-                    }
-                    intent.setType(type);
+                    sharedType = i == 0 ? getMimeType(file) : getCommonMimeType(sharedType, getMimeType(file));
+                    intent.setType(sharedType != null ? sharedType : "*/*");
 
                     Uri fileUrl = FileProvider.getUriForFile(
                         getActivity(),
@@ -227,6 +225,24 @@ private String getMimeType(String url) {
         return type;
     }
 
+    /**
+     * Returns the most specific MIME type that covers both types: the type itself when they match,
+     * {@code type/*} when only the top-level type matches, and {@code null} otherwise.
+     */
+    static String getCommonMimeType(String first, String second) {
+        if (first == null || second == null) {
+            return null;
+        }
+        if (first.equals(second)) {
+            return first;
+        }
+        int slash = first.indexOf('/');
+        if (slash > 0 && slash == second.indexOf('/') && first.regionMatches(0, second, 0, slash)) {
+            return first.substring(0, slash) + "/*";
+        }
+        return null;
+    }
+
     private boolean isFileUrl(String url) {
         return url.startsWith("file:");
     }

share/android/src/test/java/com/capacitorjs/plugins/share/SharePluginTest.java

@@ -0,0 +1,28 @@
+package com.capacitorjs.plugins.share;
+
+import static org.junit.Assert.*;
+
+import org.junit.Test;
+
+public class SharePluginTest {
+
+    @Test
+    public void getCommonMimeType_keepsMatchingType() {
+        assertEquals("image/jpeg", SharePlugin.getCommonMimeType("image/jpeg", "image/jpeg"));
+    }
+
+    @Test
+    public void getCommonMimeType_usesWildcardSubtypeForSameTopLevelType() {
+        assertEquals("image/*", SharePlugin.getCommonMimeType("image/jpeg", "image/png"));
+        assertEquals("image/*", SharePlugin.getCommonMimeType("image/*", "image/png"));
+        assertEquals("video/*", SharePlugin.getCommonMimeType("video/mp4", "video/webm"));
+    }
+
+    @Test
+    public void getCommonMimeType_returnsNullForDifferentOrUnknownTypes() {
+        assertNull(SharePlugin.getCommonMimeType("image/jpeg", "video/mp4"));
+        assertNull(SharePlugin.getCommonMimeType("image/jpeg", null));
+        assertNull(SharePlugin.getCommonMimeType(null, "image/jpeg"));
+        assertNull(SharePlugin.getCommonMimeType("imagex/png", "image/png"));
+    }
+}