fix(gui): handle paths where file name is null (#2136)(PR #2137)

* fix: Ignore invalid files

Avoid NullPointerException when using "Open files" or drag-n-drop

* refactor: Replace Stream API chain with loop

IntelliJ

* fix: Ignore invalid files

Avoid NullPointerException when using "Add files"

* fix: Fall back to complete path string

Instead of empty project name

* fix: Render tree

Project tree (sidebar) didn’t load
Toggling "View > Show flatten packages" threw a NPE here

* fix code formatting

---------

Co-authored-by: Skylot <skylot@gmail.com>

jadx-gui/src/main/java/jadx/gui/settings/JadxProject.java

@@ -10,6 +10,7 @@ import java.util.Collections;
 import java.util.List;
 import java.util.Map;
 import java.util.Objects;
+import java.util.StringJoiner;
 import java.util.function.Consumer;
 import java.util.stream.Collectors;
 
@@ -113,11 +114,19 @@ public class JadxProject {
 		} else {
 			Collections.sort(files);
 			data.setFiles(files);
-			String joinedName = files.stream()
-					.map(p -> p.getFileName().toString())
-					.filter(file -> !file.endsWith(".jadx.kts"))
-					.map(CommonFileUtils::removeFileExtension)
-					.collect(Collectors.joining("_"));
+			StringJoiner joiner = new StringJoiner("_");
+			for (Path p : files) {
+				Path fileNamePart = p.getFileName();
+				if (fileNamePart == null) {
+					joiner.add(p.toString());
+					continue;
+				}
+				String fileName = fileNamePart.toString();
+				if (!fileName.endsWith(".jadx.kts")) {
+					joiner.add(CommonFileUtils.removeFileExtension(fileName));
+				}
+			}
+			String joinedName = joiner.toString();
 			name = StringUtils.abbreviate(joinedName, 100);
 		}
 		changed();

jadx-gui/src/main/java/jadx/gui/treemodel/JRoot.java

@@ -173,7 +173,11 @@ public class JRoot extends JNode {
 			return "File not open";
 		}
 		if (count == 1) {
-			return paths.get(0).getFileName().toString();
+			Path fileNamePath = paths.get(0).getFileName();
+			if (fileNamePath != null) {
+				return fileNamePath.toString();
+			}
+			return paths.get(0).toString();
 		}
 		return count + " files";
 	}

jadx-gui/src/main/java/jadx/gui/ui/MainWindow.java

@@ -460,6 +460,9 @@ public class MainWindow extends JFrame {
 	}
 
 	private boolean openSingleFile(Path singleFile, Runnable onFinish) {
+		if (singleFile.getFileName() == null) {
+			return false;
+		}
 		String fileExtension = CommonFileUtils.getFileExtension(singleFile.getFileName().toString());
 		if (fileExtension != null && fileExtension.equalsIgnoreCase(JadxProject.PROJECT_EXTENSION)) {
 			openProject(singleFile, onFinish);