Jak utworzyć strukturę w JNA?

Question

Otrzymuję ten błąd, gdy uruchamiam poniższy kod;

Exception in thread "AWT-EventQueue-0" java.lang.Error: Structure.getFieldOrder() on class javaapplication2.NewJFrame$APPBARDATA returns names ([cbSize, hWnd, jCallbackMessage, jEdge, rc, sParam]) which do not match declared field names ([]) 
    at com.sun.jna.Structure.getFields(Structure.java:872) 
    at com.sun.jna.Structure.deriveLayout(Structure.java:983) 
    at com.sun.jna.Structure.calculateSize(Structure.java:908) 
    at com.sun.jna.Structure.calculateSize(Structure.java:896) 
    at com.sun.jna.Structure.allocateMemory(Structure.java:357) 
    at com.sun.jna.Structure.<init>(Structure.java:191) 
    at com.sun.jna.Structure.<init>(Structure.java:180) 
    at com.sun.jna.Structure.<init>(Structure.java:167) 
    at com.sun.jna.Structure.<init>(Structure.java:159) 
    at javaapplication2.NewJFrame$APPBARDATA.<init>(NewJFrame.java:31) 
    at javaapplication2.NewJFrame.<init>(NewJFrame.java:56) 
    at javaapplication2.NewJFrame$7.run(NewJFrame.java:255) 
    at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:251) 
    at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:721) 
    at java.awt.EventQueue.access$200(EventQueue.java:103) 
    at java.awt.EventQueue$3.run(EventQueue.java:682) 
    at java.awt.EventQueue$3.run(EventQueue.java:680) 
    at java.security.AccessController.doPrivileged(Native Method) 
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76) 
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:691) 
    at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:242) 
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:161) 
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:150) 
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:146) 
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:138) 
    at java.awt.EventDispatchThread.run(EventDispatchThread.java:91) 

moja klasa:

class APPBARDATA extends Structure { 

    WinUser.DWORD cbSize; 
    WinUser.HWND hWnd; 
    WinUser.UINT_PTR uCallbackMessage; 
    WinUser.UINT_PTR uEdge; 
    WinUser.RECT rc; 
    WinUser.LPARAM lParam; 

    @Override 
    protected List getFieldOrder() { 
     return Arrays.asList(new String[]{"cbSize", "hWnd", "uCallbackMessage", "uEdge", "rc", "lParam"}); 
    } 
} 

    APPBARDATA pdata = new APPBARDATA(); 
    pdata.lParam = new WinUser.LPARAM(0); 
    pdata.cbSize = new WinUser.DWORD(32); 
    pdata.hWnd = WinUser.HWND_BROADCAST; 

Co jest nie tak?

Answer 1

Oznacz swoje atrybuty jako publiczne, ponieważ as specified in the doc, JNA użyj class.getFields(), aby uzyskać listę atrybutów.

Javadoc z Class.getFields():

Returns an array containing Field objects reflecting all the accessible public fields of the class or interface represented by this Class object. ...