Question

您好我正在尝试使用Jsoup创建从站点上的所有jpgs中提取的图像的ArrayList。我遇到了nullPointerException，好像for循环不在那里。

try {
    Document doc = Jsoup.connect("www.enterwebsitehere.com").get();
    jpgs = doc.select("img[src$=.jpg]");

    for (int countPics = 0; countPics > 10; countPics++) {
        Element currentPic = jpgs.get(countPics);

        String currentPicString = currentPic.toString();
        int startofAddress = currentPicString.indexOf("http:");
        int endofAddress = (currentPicString.indexOf(".jpg") + 4);
        String urlOfImage = currentPicString.substring(startofAddress, endofAddress);

        URL url = new URL(urlOfImage);
        Image currentImage = ImageIO.read(url);
        imageList.add(currentImage);
    }


} catch (MalformedURLException e) {
} catch (Exception e) {
    e.printStackTrace();
}

我相信我需要在catch块之外引入一些变量吗？

感谢您提供任何帮助。

EHarpham

Answer 1

CountPics＆gt; 10正在评估为假。（0> 10）是假的。

Answer 2

我相信你的意思是：for (int countPics = 0; countPics < 10; countPics++)

请注意将countPics > 10转换为countPics < 10

如何在try catch块中使用for循环

2 个答案: