帮忙看看这段程序是什么意思！！

[timi先生]

public class Solution {
    public static void main(String[] args) throws Exception {
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
        String fileName = null;
        FileOutputStream fos = null;
        TreeSet<String> set = new TreeSet<String>();
        while (true){
            String path = reader.readLine();
             if(path.equals("end")||path.equals("结束"))
            {
                break;
            }
            set.add(path);
        }
        while(set.size() > 0){
            String path = set.pollFirst();
            if (fileName == null) {
                fileName = path.substring(0, path.lastIndexOf("."));
                fos = new FileOutputStream(fileName);
            }
            
            byte[] data = new byte[1024];
            int len;
            FileInputStream fis = new FileInputStream(path);
            while ((len = fis.read(data)) > 0){
                fos.write(data, 0, len);
            }
            fis.close();
        }
        fos.close();
        reader.close();
    }
}

[qybao]

if(fileName==null)去掉，否则下一次循环fileName不再是null，就不会进入if分支

[亦夜]

或者手动将fileName置空

[KeepSayingNo]

读个输入再将其输出

[xiong_zai_]

把所有读入的文件名的内容写到第一个文件名去后缀的文件中去

[如此美丽的你]

复制文件并去掉后缀名