Image comparison Failure | java -

    import java.awt.image.bufferedimage; import javax.imageio.imageio; import java.io.ioexception; import java.net.url; public class imagecompare {     public static void main(string args[])       {         bufferedimage img1 = null;         bufferedimage img2 = null;         try {           url url1 = new url("http://www.desktopid.com/wp-content/uploads/2015/05/apple-logo-free-desktop-wallpapers.jpg");           url url2 = new url("http://www.desktopid.com/wp-content/uploads/2015/05/apple-logo-free-desktop-wallpapers.jpg");           img1 = imageio.read(url1);           img2 = imageio.read(url2);         } catch (ioexception e) {           e.printstacktrace();         }         int width1 = img1.getwidth(null);         int width2 = img2.getwidth(null);         int height1 = img1.getheight(null);         int height2 = img2.getheight(null);         if ((width1 != width2) || (height1 != height2)) {           system.err.println("error: images dimensions mismatch");           system.exit(1);         }         long diff = 0;         (int y = 0; y < height1; y++) {           (int x = 0; x < width1; x++) {             int rgb1 = img1.getrgb(x, y);             int rgb2 = img2.getrgb(x, y);             int r1 = (rgb1 >> 16) & 0xff;             int g1 = (rgb1 >>  8) & 0xff;             int b1 = (rgb1      ) & 0xff;             int r2 = (rgb2 >> 16) & 0xff;             int g2 = (rgb2 >>  8) & 0xff;             int b2 = (rgb2      ) & 0xff;             diff += math.abs(r1 - r2);             diff += math.abs(g1 - g2);             diff += math.abs(b1 - b2);           }         }         double n = width1 * height1 * 3;         double p = diff / n / 255.0;         system.out.println("diff percent: " + (p * 100.0));       }  } 

this simple code compares 2 images , returns percent difference, beginner, obstructed following error while running program .

> javax.imageio.iioexception: can't input stream url!     @ javax.imageio.imageio.read(unknown source)     @ imager.imagecompare.main(imagecompare.java:16) caused by: java.io.ioexception: server returned http response code: 403 url: http://www.desktopid.com/wp-content/uploads/2015/05/apple-logo-free-desktop-wallpapers.jpg     @ sun.net.www.protocol.http.httpurlconnection.getinputstream(unknown source)     @ java.net.url.openstream(unknown source)     ... 2 more exception in thread "main" java.lang.nullpointerexception     @ imager.imagecompare.main(imagecompare.java:21) 

any idea did wrong? getting url , passing ? appreciated.