title: Setting the wallpaper in Windows using Java
body: <p>I'm trying to set the wallpaper in Windows 7 using Java. I've tried using the code from the answers <a href="https://stackoverflow.com/a/22819371/5403773">here</a> and <a href="https://stackoverflow.com/a/4750765/5403773">here</a>. It works perfectly in Windows 8 and 10, but not in 7. There are no errors, it just doesn't do anything. I've tried setting different 1920x1080 wallpapers (that's the resolution set in the Control panel) and different file formats (png, jpg, bmp) and running the program on a few different computers. The code I have after the line that's supposed to set the wallpaper runs fine. I'm using JNA version 4.2.0 and Java 8 update 60. </p>
  
  <p>Is there any way I can set the wallpaper in Windows 7 using Java?</p>
  
  <p>EDIT:</p>
  
  <p>Here's my code:</p>
  
  <pre><code>import java.util.HashMap;
  
  import com.sun.jna.Native;
  import com.sun.jna.platform.win32.WinDef.UINT_PTR;
  import com.sun.jna.win32.StdCallLibrary;
  import com.sun.jna.win32.W32APIFunctionMapper;
  import com.sun.jna.win32.W32APITypeMapper;
  
  public class WallpaperChanger {
  
      public interface SPI extends StdCallLibrary {
  
          long SPI_SETDESKWALLPAPER = 20;
          long SPIF_UPDATEINIFILE = 0x01;
          long SPIF_SENDWININICHANGE = 0x02;
  
          @SuppressWarnings("serial")
          SPI INSTANCE = (SPI) Native.loadLibrary("user32", SPI.class,
                  new HashMap&lt;Object, Object&gt;() {
                      {
                          put(OPTION_TYPE_MAPPER, W32APITypeMapper.UNICODE);
                          put(OPTION_FUNCTION_MAPPER,
                                  W32APIFunctionMapper.UNICODE);
                      }
                  });
  
          boolean SystemParametersInfo(UINT_PTR uiAction, UINT_PTR uiParam,
                  String pvParam, UINT_PTR fWinIni);
      }
  
      public static void main(String[] args) {
          System.out.println("changing");
  
          String filename = "C:\\wallpapers\\wallpaper.jpg";
  
          SPI.INSTANCE.SystemParametersInfo(
                  new UINT_PTR(SPI.SPI_SETDESKWALLPAPER), new UINT_PTR(0),
                  filename, new UINT_PTR(SPI.SPIF_UPDATEINIFILE
                          | SPI.SPIF_SENDWININICHANGE));
          System.out.println("changed");
      }
  
  }
  </code></pre>
  
  <p>By 'it does not work' I mean that the code runs but wallpaper doesn't change.</p>