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SetTimer in user32.dll

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I am evaluating xFunction and I tried to use the timer services of user32.dll. I wrote a class Timer with the following code:


import com.excelsior.xFunction.*;

import javax.swing.*;

public class Timer {

   public static void main(String[] a) {

       try {

           Callback timerCallback = new TimeoutCallback();

           xFunction f = new xFunction("user32","int SetTimer(int,int,int,TimeoutCallback)");

           Argument[] args = new Argument[4];

           args[0] = new Argument(0); //no window handle

           args[1] = new Argument(0);

           args[2] = new Argument(5000); //wait for 5 seconds

           args[3] = new Argument(timerCallback);

           int i = ((Integer)f.invoke(args)).intValue();

           System.out.println(" Timer Handle = " + i);

           //without the lines below the program exits immediatelly

           JFrame frame = new JFrame("SetTimer test");



       } catch (Exception e) {





class TimeoutCallback extends Callback{

   public String defineSignature(){

    return "void timeout(int,int,int,long)";


    public void timeout(int a, int b, int c, long d){

        System.out.println("Timeout received!");




Although the return value indicates success (i get a non-null timer ID), no call is made to my callback. What am I doing wrong here?

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I think that the problem is in the SetTimer function, because the C version of such example do not work as well.

#include <windows.h>

void MyTimerProc(int a , int b, int c, int d) {

int main(void) {
   int a = SetTimer(NULL,         
       (TIMERPROC) MyTimerProc); 
   printf("%d\n", a);

To compile one may use the following command-line:

cl timer.c user32.lib

The description of the SetTimer is foggy and probably it  does not work if invoked with the first parameter NULL (hWnd).

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