java - 为什么我的 Java 代码会导致 netbeans 卡住

Question

我一直在做一项工作，当我尝试运行它时，我的 IDE 卡住了，我必须使用任务管理器将其关闭。

知道为什么吗？我知道这与我使用的迭代器和 while 循环有关。

有人能发现吗？下面是servlet代码的一部分:

try {
        List<FileItem> fields = upload.parseRequest(request);

        Iterator<FileItem> it = fields.iterator();




        //starting conversion from file to sample


        //creating a container to hold the samples
        ArrayList<sample> samplelist = new ArrayList();

        while (it.hasNext()) {

            sample c = new sample();
            FileItem fileItem = it.next();

            c.setFileName(fileItem.getName());
            c.setPayload(fileItem.getString());
            samplelist.add(c);
        }

        //looping through uploaded samples to split code into lines
        for (int i = 0; i < samplelist.size(); i++) {
            sample current = new sample();
            current = samplelist.get(i);

            //splitting whole code block into lines based on ;
            String[] temp;
            temp = current.getPayload().split(";");

            //going through split lines and adding them to the sample's rawcode
            //arraylist after checking for for loops
            for (int j = 0; j < temp.length; j++) {

                // current.Raw_Code.add(temp[j]);
                String current_line = temp[j];




                current.Raw_Code.add(current_line);

            }




        }

//testing
        System.out.print("starting testing");
        for (int i = 0; i < samplelist.size(); i++) {
            sample current = new sample();
            current = samplelist.get(i);
            System.out.print("File name <br/>");
            current.getFileName();
            System.out.print("lines detected <br/>");

            Iterator itr = current.Raw_Code.iterator();

           //this while loop started to cause the problem

             while(itr.hasNext()){
             System.out.print("x");   
             }
        }




    } catch (FileUploadException e) {
        e.printStackTrace();
    }



    out.close();
    return;

Answer 1

就在这里:

while(itr.hasNext()){
    System.out.print("x");   
}

您没有调用 itr.next()，因此迭代器不会迭代。 :) 在 while 循环中添加 itr.next() 将纠正该问题。