使用JNA和EnumWindows的问题

Question

I'm experimenting with JNA, and this is the first program I try to run. I copied it from the reference, but, when i run it, he finds 412 windows ... and I'm quite sure I've not that many window opened right now :) Can please someone explain me the behaviour of the program?

import com.sun.jna.Pointer;
import com.sun.jna.win32.StdCallLibrary.StdCallCallback;
import com.sun.jna.Native;
import com.sun.jna.win32.StdCallLibrary;

public class Main {
// Equivalent JNA mappings
    public interface User32 extends StdCallLibrary {
        User32 INSTANCE = (User32) Native.loadLibrary("user32", User32.class);

        interface WNDENUMPROC extends StdCallCallback {
            boolean callback(Pointer hWnd, Pointer arg);
        }

        boolean EnumWindows(WNDENUMPROC lpEnumFunc, Pointer arg);
    }

    public static void main(String[] args) {
        User32 user32 = User32.INSTANCE;

        user32.EnumWindows(new User32.WNDENUMPROC() {
            int count;
            public boolean callback(Pointer hWnd, Pointer userData) {
                System.out.println("Found window " + hWnd + ", total " + ++count);
                return true;
            }
        }, null);
    }
}

Answer 1

In Windows, almost everything is a Window. Here are some changes to your code that will show some of the window titles/text:

import com.sun.jna.Pointer;
import com.sun.jna.Native;
import com.sun.jna.win32.StdCallLibrary;

public class JNA_Main {
    // Equivalent JNA mappings
    public interface User32 extends StdCallLibrary {
        User32 INSTANCE = (User32) Native.loadLibrary("user32", User32.class);

        interface WNDENUMPROC extends StdCallCallback {
            boolean callback(Pointer hWnd, Pointer arg);
        }

        boolean EnumWindows(WNDENUMPROC lpEnumFunc, Pointer arg);

        int GetWindowTextA(Pointer hWnd, byte[] lpString, int nMaxCount);
    }

    public static void main(String[] args) {
        final User32 user32 = User32.INSTANCE;

        user32.EnumWindows(new User32.WNDENUMPROC() {

            int count;

            public boolean callback(Pointer hWnd, Pointer userData) {
                byte[] windowText = new byte[512];
                user32.GetWindowTextA(hWnd, windowText, 512);
                String wText = Native.toString(windowText);
                wText = (wText.isEmpty()) ? "" : "; text: " + wText;
                System.out.println("Found window " + hWnd + ", total " + ++count + wText);
                return true;
            }
        }, null);
    }
}

Please ask if anything is unclear.