Fix exception when editing URL file (#8009)

* Fix exception when editing URL file

Fixes #8008

* fix checkstyle and add changelog

CHANGELOG.md

@@ -29,6 +29,7 @@ Note that this project **does not** adhere to [Semantic Versioning](http://semve
 
 ### Fixed
 
+- We fixed an issue where an exception ocurred when a linked online file was edited in the entry editor [#8008](https://github.com/JabRef/jabref/issues/8008)
 - We fixed an issue when checking for a new version when JabRef is used behind a corporate proxy. [#7884](https://github.com/JabRef/jabref/issues/7884)
 - We fixed some icons that were drawn in the wrong color when JabRef used a custom theme. [#7853](https://github.com/JabRef/jabref/issues/7853)
 - We fixed an issue where the `Aux file` on `Edit group` doesn't support relative sub-directories path to import. [#7719](https://github.com/JabRef/jabref/issues/7719).

src/main/java/org/jabref/gui/linkedfile/LinkedFilesEditDialogViewModel.java

@@ -1,5 +1,7 @@
 package org.jabref.gui.linkedfile;
 
+import java.net.MalformedURLException;
+import java.net.URL;
 import java.nio.file.Path;
 import java.util.List;
 import java.util.Optional;
@@ -125,7 +127,16 @@ public ObjectProperty<ExternalFileType> selectedExternalFileTypeProperty() {
     }
 
     public LinkedFile getNewLinkedFile() {
-        return new LinkedFile(description.getValue(), Path.of(link.getValue()), monadicSelectedExternalFileType.getValue().map(ExternalFileType::toString).orElse(""));
+        String fileType = monadicSelectedExternalFileType.getValue().map(ExternalFileType::toString).orElse("");
+
+        if (LinkedFile.isOnlineLink(link.getValue())) {
+            try {
+                return new LinkedFile(description.getValue(), new URL(link.getValue()), fileType);
+            } catch (MalformedURLException e) {
+                return new LinkedFile(description.getValue(), link.getValue(), fileType);
+            }
+        }
+        return new LinkedFile(description.getValue(), Path.of(link.getValue()), fileType);
     }
 
     private String relativize(Path filePath) {