CrossLink : Bridging Java and C/C++ Codebases

Overview

Architecture

Figure: CrossLink System Architecture

JNI Indexing and Performance

• Index Construction -

  Upon initialization, CrossLink scans all c and cpp files within the workspace. It extracts function names that adhere to the standard JNI naming convention (i.e., Java_PackageName_ClassName_MethodName). These function signatures are mapped to their corresponding file paths in the JNI Index. This index is computed once and is only rebuilt when changes are detected in the C/C++ source files. These file changes are detected by File Watcher. File Watcher triggers re-analysis in the dependency analyzer and the constant analyzer.

• Lookup and Live Highlighting -

  To provide live feedback in the editor, CrossLink minimizes parsing overhead by scanning only the active Java file. The process follows two steps:

  • (1) Native Scanning:

    The tool scans the Java file, specifically looking for lines that include the native keyword. It captures the package, class, and method names to create the expected C++ function name.

  • (2) Index Query:

    These computed names are checked against the pre-built JNI Index. If a match is found, the connection is noted, and the link is highlighted in green. If no match is found, the link gets highlighted in red, providing immediate visual feedback about the broken link.

Features

Dependency Visualization & Verification

• Dependency and JNI Link Graph: The tool creates a visual graph of file-level dependencies. It clearly marks nodes where JNI implementations are missing. This gives developers a high-level view of the project’s binding status.
• JNI Link Report: While the graph shows file dependencies,the Link Report panel provides detailed, method-level dependencies in a table format. It lists every specific Java-to-C++ method link.

Interactive Navigation

• Live Link Highlighting: As developers type, the tool highlights native method declarations in real-time (green for linked, red for broken). This prevents waiting for runtime UnsatisfiedLinkError exceptions. As explained in below code snippet.
• 🟢 Green: Java method declaration present in some C/C++ file.
• 🔴 Red: Java method declaration Missing indicating broken link.
• Cross-language navigation (Java → C++): Developers can click on a successfully linked Java native method to quickly jump to its corresponding C++ implementation definition. This simplifies code exploration. In below figure we can see Goto implementation option above the highlighted link.

Figure: Link highlighting with option to jump to C++ implementation

Cross-Language Code Highlighting

• Highlights System.loadLibrary() calls
• Platform-aware extension detection (.dll, .so, .dylib)
• Hover information: Detailed information about library status and native method implementation when hovering over highlighted code
• Color-coded status:
  • 🟢 Green: Library exists with correct extension or native method has C++ implementation
  • 🔴 Red: Library file is missing or native method implementation is missing
  • 🔵 Blue: Library exists but has wrong extension for current platform
• Platform Detection: automatically detects OS and expects appropriate library extensions.
  • Windows: .dll
  • Linux: .so
  • macOS: .dylib

Constants Management

• Constants analyzer: Scans for constants across Java and C++ files
• Naming suggestions: Provides constant naming based on context and usage
• Magic number identification: Detects numbers that should be extracted as constants
• Context-aware categorization: Groups constants by type, file, or usage context

Interactive Dashboard

• Webview-based control panel: UI for managing all features
• Real-time statistics: Shows dependency counts, connection metrics, and constants analysis
• Search and filtering: Advanced filtering capabilities for all data (or in simple terms a search button)
• Quick actions: Context menus for common refactoring operations (Copy or Move)

Requirements

• Visual Studio Code
• Java projects using JNI
• C++ projects interfacing with Java

Example

public class HelloJNI {
    static {
        System.loadLibrary("hello");
    }

    private native void sayHello();
    public native int add(int a, int b);
    public native String getMessage(String name);
}

Getting Started

1. Clone the repository

   git clone https://github.com/yourusername/crosslink.git

2. Open the project in VS Code
3. Press F5 (or go to Run → Start Debugging) click on "Debug Anyway" if popup comes.
4. Open any Java file from a JNI project

Tool Evaluation Study

Here is the document which was shared to the participants before the task, It contains necessary information and task details.

Video Demonstration