JNA Keyboard Hook in Windows

It appears you need to call GetMessage or PeekMessage, which is odd - it is not mentioned in the documentation for Hooks or LowLevelKeyboardProc. I don't know enough about this part of the API to guess at the reason.

I just used the example classes:

import com.sun.jna.examples.win32.*;public class Callback {  public static User32.HHOOK hHook;  public static User32.LowLevelKeyboardProc lpfn;  public static volatile boolean quit = false;  public static void main(String[] args) throws Exception {    W32API.HMODULE hMod = Kernel32.INSTANCE.GetModuleHandle(null);    lpfn = new User32.LowLevelKeyboardProc() {      public W32API.LRESULT callback(int nCode, W32API.WPARAM wParam,          User32.KBDLLHOOKSTRUCT lParam) {        System.out.println("here");        quit = true;        return User32.INSTANCE.CallNextHookEx(hHook, nCode, wParam, lParam            .getPointer());      }    };    hHook = User32.INSTANCE.SetWindowsHookEx(User32.WH_KEYBOARD_LL, lpfn, hMod,        0);    if (hHook == null)      return;    User32.MSG msg = new User32.MSG();    while (!quit) {      User32.INSTANCE.PeekMessage(msg, null, 0, 0, 0);      Thread.sleep(100);    }    if (User32.INSTANCE.UnhookWindowsHookEx(hHook))      System.out.println("Unhooked");  }}

A minimalist example:

import com.sun.jna.platform.win32.Kernel32;import com.sun.jna.platform.win32.User32;import com.sun.jna.platform.win32.WinDef.HINSTANCE;import com.sun.jna.platform.win32.WinDef.LPARAM;import com.sun.jna.platform.win32.WinDef.LRESULT;import com.sun.jna.platform.win32.WinDef.WPARAM;import com.sun.jna.platform.win32.WinUser.HOOKPROC;public class MainTestKeyHook {    public static void main(String[] args) throws Exception {        HOOKPROC hookProc = new HOOKPROC_bg();        HINSTANCE hInst = Kernel32.INSTANCE.GetModuleHandle(null);        User32.HHOOK hHook = User32.INSTANCE.SetWindowsHookEx(User32.WH_KEYBOARD_LL, hookProc, hInst, 0);        if (hHook == null)            return;        User32.MSG msg = new User32.MSG();        System.err.println("Please press any key ....");        while (true) {            User32.INSTANCE.GetMessage(msg, null, 0, 0);        }       }}class HOOKPROC_bg implements HOOKPROC {    public HOOKPROC_bg() {    }    public LRESULT callback(int nCode, WPARAM wParam, LPARAM lParam) {        System.err.println("callback bbbnhkilhjkibh nCode: " + nCode);        return new LRESULT(0);    }}