JStudio

A Java reverse engineering and static analysis IDE for analyzing, decompiling, and transforming Java bytecode.

Powered by YABR

Features

Multi-View Editor

Code Views

• Source - Decompiled Java with syntax highlighting
• Bytecode - JVM instructions with color-coded opcodes

IR Views

• SSA IR - Static Single Assignment intermediate representation
• AST IR - Abstract Syntax Tree representation

Graph Views

• Control Flow - Basic block CFG with bytecode/IR toggle
• Program Dependence - Data and control dependency graph
• System Dependence - Interprocedural dependence graph
• Code Property - Unified code property graph
• Call Graph - Method call hierarchy with depth control and invoke-type colored edges (virtual, static, special, interface, dynamic)

Other Views

• Const Pool - Constant pool entry browser with filtering
• Attributes - Class, field, and method attributes tree view
• Statistics - Class metrics dashboard with charts (method sizes, complexity, opcode distribution)
• Hex - Raw class file bytes

Analysis Tools

• Call Graph - Method call hierarchy visualization
• Dependencies - Class dependency graphs with cycle detection
• Data Flow - Forward/backward flow analysis with taint tracking
• Pattern Search - Find method calls, field access, allocations, type casts
• Similarity - Detect duplicate and renamed methods
• Simulation - Find opaque predicates, dead code, decryption patterns
• Strings - Extract and search constant pool strings
• Query Explorer - Flexible query builder for code searches
• Cross-References - Bidirectional symbol reference tracking

Bytecode Debugger

• Breakpoints - Set breakpoints on any instruction
• Stepping - Step into, over, out, run to cursor
• Variable Inspection - View and edit locals and stack
• Call Stack - Navigate stack frames
• Execution Modes - Stub mode (fast) or recursive mode (full)
• Tracing - Record execution history, export to Markdown

Heap Analysis

• Object Browser - Explore allocated objects by class
• Field Inspection - View object fields and arrays
• Snapshots - Capture and compare heap state
• Forensics - Track object creation and mutations

Test Generation

• Method Execution - Run methods with custom arguments
• Fuzz Testing - Automated input generation
• JUnit Export - Generate JUnit 4/5 test cases

Deobfuscation

• String Detection - Find encrypted strings
• Decryptor ID - Locate decryption methods
• Auto-Decrypt - Execute decryptors to reveal strings
• Name Recovery - Deobfuscate class/method/field names

Code Transformation

• Script Editor - Custom scripting language for AST/bytecode/IR manipulation
• Optimizations - Constant folding, copy propagation, dead code elimination, strength reduction
• Stack Frames - Recompute stack map frames

UI

• Tabbed editor with multiple views per class
• Navigator tree with package hierarchy
• Properties panel for metadata
• Console with multi-level logging
• 8 built-in themes

Building & Running

./gradlew run              # Run directly
./gradlew build            # Compile + test + create JAR
./gradlew shadowJar        # Create fat JAR only

java -jar build/libs/JStudio.jar           # Launch GUI
java -jar build/libs/JStudio.jar --cli     # Launch CLI

Usage

1. Open: File -> Open (Ctrl+O) to load JAR, directory, or class file
2. Navigate: Browse packages and classes in the tree
3. View: Switch views using the dropdown or View menu
4. Analyze: Use Analysis menu for graphs, dependencies, searches
5. Debug: Right-click method -> Debug Method
6. Execute: Right-click method -> Execute Method
7. Transform: Use Transform menu for scripts and optimizations

Keyboard Shortcuts

File

| Action | Shortcut | |--------|----------| | Open JAR/Class | Ctrl+O | | Open Recent | Ctrl+Shift+O | | Save Project | Ctrl+S | | Save Project As | Ctrl+Shift+S | | Export Class | Ctrl+Alt+E | | Export as JAR | Ctrl+Shift+J | | Close Tab | Ctrl+W | | Close Project | Ctrl+Shift+W | | Exit | Ctrl+Q |

Navigation

| Action | Shortcut | |--------|----------| | Go to Class | Ctrl+G | | Go to Line | Ctrl+L | | Navigate Back | Alt+Left | | Navigate Forward | Alt+Right |

Edit

| Action | Shortcut | |--------|----------| | Copy | Ctrl+C | | Find in File | Ctrl+F | | Find in Project | Ctrl+Shift+F | | Add Bookmark | Ctrl+B | | View Bookmarks | Ctrl+Shift+B | | Add Comment | Ctrl+; | | Preferences | Ctrl+, |

Views

| Action | Shortcut | |--------|----------| | Source View | F5 | | Bytecode View | F6 | | IR View | F7 | | Hex View | F8 | | Refresh | Ctrl+F5 | | Word Wrap | Alt+Z |

Panels

| Action | Shortcut | |--------|----------| | Toggle Navigator | Ctrl+1 | | Toggle Properties | Ctrl+2 | | Toggle Console | Ctrl+3 |

Font

| Action | Shortcut | |--------|----------| | Increase Font | Ctrl+= | | Decrease Font | Ctrl+- | | Reset Font | Ctrl+0 |

Analysis

| Action | Shortcut | |--------|----------| | Run Analysis | F9 | | Simulation Analysis | F10 | | Query Explorer | Ctrl+Shift+Q | | Call Graph | Ctrl+Shift+G |

Transform

| Action | Shortcut | |--------|----------| | Apply Transforms | Ctrl+Shift+T | | Script Editor | Ctrl+Alt+S | | String Deobfuscation | Ctrl+Shift+D |

VM

| Action | Shortcut | |--------|----------| | Bytecode Debugger | F11 | | VM Console | Ctrl+Shift+C | | Execute Method | Ctrl+Shift+E | | Heap Forensics | Ctrl+Shift+H |

Help

| Action | Shortcut | |--------|----------| | Keyboard Shortcuts | F1 |

CLI Mode

java -jar JStudio.jar --cli --help

Commands

# Display info
java -jar JStudio.jar --cli info app.jar
java -jar JStudio.jar --cli info app.jar --stats --json

# Run plugin/script
java -jar JStudio.jar --cli run app.jar -p script.groovy
java -jar JStudio.jar --cli run app.jar -p plugin.jar -o results.json

# Interactive REPL
java -jar JStudio.jar --cli repl app.jar

# Batch processing
java -jar JStudio.jar --cli batch *.jar -p analyzer.groovy --parallel

REPL Commands

| Command | Description | |---------|-------------| | :load <path> | Load JAR/class/directory | | :classes [pattern] | List classes | | :methods <class> | List methods | | :info <class> | Show class details | | :run <script> | Execute script | | :quit | Exit |

Dependencies

• FlatLaf - Swing look and feel
• RSyntaxTextArea - Syntax highlighting
• JGraphX - Graph visualization
• JavaParser - Java parsing
• YABR - Bytecode analysis
• picocli - CLI framework
• JLine - Terminal handling
• Groovy - Scripting support

License

MIT