Retrieving item text with JNA and SendMessage() - jna

Question

I am attempting to retrieve the item text from a Win32 ListView-like control. I am using JNA and SendMessageW() to send LVM_GETITEMTEXTW to the control. I have been successful at retrieving the item count (via LVM_GETITEMCOUNT) but am stumped at this point. My User32 class is setup like so:
public interface MyUser32 extends User32 {
MyUser32 INSTANCE = (MyUser32)Native.loadLibrary("user32", MyUser32.class);
LRESULT SendMessageW(HWND hWnd, int msg, WPARAM wParam, LVITEM lParam);
}
My LVITEM class is setup like so:
public class LVITEM extends Structure{
public LVITEM() {
pszText = new Memory(MEMSIZE);
cchTextMax = MEMSIZE;
}
private static final int MEMSIZE = 256;
public UINT mask;
public int iItem;
public int iSubItem;
public UINT state;
public UINT stateMask;
public Pointer pszText;
public int cchTextMax;
public int iImage;
public LPARAM lParam;
public int iIndent;
protected List<String> getFieldOrder() {
return Arrays.asList(new String[] { "mask", "iItem", "iSubItem", "state", "stateMask", "pszText", "cchTextMax", "iImage", "lParam", "iIndent"});
}
}
And the code that calls it all is like so:
MyUser32 u32 = MyUser32.INSTANCE;
LVITEM lvItem = new LVITEM();
WPARAM wPar = new WPARAM(1);
...
lvItem.iSubItem = 0;
res = u32.SendMessageW(handle, LVM_GETITEMTEXTW, wPar, lvItem);
System.out.println(res.intValue());
s = lvItem.pszText.getString(0);
System.out.println(s);
I've left out a bit of the code but I believe those are the important parts. My issue is that when I print out res.intValue() it is always 0 (meaning no text was returned) and when I print out the string value of pszText it is always some garbage characters. I'm completely stumped at this point so any suggestions are greatly appreciated. Thanks.