!!! note "Debugging Android apps"
    Looking to dive head-first into Android application debugging? Read on and then head to the [Android Debugging](android-debugging.md) section.

Debuggers are special modules that attach to existing code units. They do not produce additional units; instead, they provide **specialized actions**, accessible graphically via the *Debugger* menu in the GUI client.

[![An example of two debugger units (Dalvik and native) connected to an Android app](img/jeb-menu-debugger.png)](img/jeb-menu-debugger.png)

!!! note "Scripting"
    Debugger modules offer a rich API. GUI clients can only reflect those functionality partly. Visit the blog for more information on how to use the debuggers API to perform advanced dynamic analysis of applications.

# Availability

JEB ships with debuggers for:

- Android DEX bytecode: the debugger implements JDWP
- Machine code (x86/x86-64, ARM/ARM64, MIPS, etc.): the debugger implements the gdb/lldb protocol

# Attaching to a Target

- Open a code view representing the code unit to be debugged.
- Execute *Debugger, Start...*
- Specify the target (e.g. machine/process, hostname/port, etc.) and debugging options
- Click *Attach*

One or more debugger unit(s) will be created, depending on your target application.

## Dalvik Debugging

Debugging Dalvik code is supported by JEB. More information can be found in the next section, specific to Android (APK) debugging.

[![Attaching to a pseudo-local target for dalvik debugging](img/jeb-dbg-attach.png)](img/jeb-dbg-attach.png)

## Remote Debugging

Debugging native code is supported by JEB through its gdb/lldb debugging client module. After setting up gdbserver (or lldb-server) on your target, specify the hostname and port to debug x86, arm, and mips code.

[![Attaching to a remote target for native code debugging](img/c93b3a55-small.png)](img/c93b3a55.png)

!!! note
    The gdb/lldb client module is also used to debug native code stored inside Android applications. Refer to the next section "Android Debugging" for detailed explanations.

# Views

The GUI client will also open automatically open views that represent the debugger units. Those views are:

- Threads
- Breakpoints
- Local variables and registers
- Memory and live disassembly (if applicable)
- Current stack (if applicable)
- Log view

[![An ongoing debugging session](img/jeb-dbg-views.png)](img/jeb-dbg-views.png)

You may want to switch to a custom layout to better accommodate those additional views. The above pictures shows an on-going debugging session of an Android app. A custom layout is used:

- the bytecode debugger views are in the top-right hand quadrant
- the process code debugger views are in the bottom-right hand quadrant

A breakpoint can also be seen, as well as the about-to-be-executed line of code.

# Basic Commands

The basic commands are accessible from the *Debugger* menu.

- Detach from or restart the debugging session
- Pause, resume, or terminate the target
- Suspend or resume threads
- Set breakpoints (on code execution, on field access, on field modification)
- Step execution (into, over, or out of a routine)
- Add dynamic code units to a debugger (e.g. dex units to a dalvik debugger, native code units to a native debugger) , while a debugging session is active. This is useful when code objects are retrieved and need to be added to a project after an analysis was started.

The live values of variables and registers can also be examined by hovering over an item representing them.

# Advanced Commands

Advanced debugging commands can be used via the *Console* view. This view is linked to *command interpreters* offered by the currently focused unit. Debuggers offer command interpreter to perform advanced tasks such as:

- Searching patterns in memory
- Examining objects
- Creating objects or invoking methods
- Custom tasks specific to a given debugger that cannot be generically represented by the GUI client

[![An expanded *Console* view with an interpreter connected to the Dalvik Bytecode debugger](img/jeb-dbg-console.png)](img/jeb-dbg-console.png)

!!! note "Learn more"
    A detailed overview of the interpreters' features can be found on our blog.

# Android Debugging

Learn more about Android application debugging by going through [this next manual page](android-debugging.md).