CODEWITHSUNDEEP
javaswinghwnd
DecentWig
DecentWig

Reputation: 23

How to get windows handle from JFrame

I have an application which is a GUI written using Java Swing. Within the app I'm using a rest API which requires a window handle (HWND) as one of it's parameters (the API creates a JPG and displays it on the selected window. I need a way of programmatically getting the HWND of a JFrame to pass into this API, is this possible?

I have seen the following code recommended:

import sun.awt.windows.WComponentPeer;

public static long getHWnd(Frame f) {
   return f.getPeer() != null ? ((WComponentPeer) f.getPeer()).getHWnd() : 0;
}

However, the getPeer() method is deprecated and the above code throws a NoSuchMethodError.

Upvotes: 0

Views: 163

Answers (1)

Cardinal System
Cardinal System

Reputation: 3430

The Componenet#getPeer() method was removed in Java 9. Unless you are using Java 8, you will have to use reflection to get the native handle. Here is an example (untested):

public static Optional<Long> getNativeHandle(Window window) {
    try {
        Field field = Component.class.getDeclaredField("peer");
        field.setAccessible(true);

        Object peer = field.get(window);
        field.setAccessible(false);

        if (peer == null)
            return Optional.empty();

        Method method = peer.getClass().getMethod("getHWnd");
        long handle = (long) method.invoke(peer);

        return Optional.of(handle);
    } catch (Exception e) {
        return Optional.empty();
    }
}

Upvotes: 0

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