扫描仪中的NoSuchElementException [英] NoSuchElementException in Scanner

问题描述

我正在研究一种解析器(业余项目)，它需要一个Cpp文件，读取文件中的注释，然后尝试基于该文件创建头文件.

I am working on a kind-of parser (hobby project) which takes a Cpp file, reads through the comments in the file, and then tries to create a header file based on that.

我面临的问题是java.util.Scanner即将读取第一行时.程序停止并给我NoSuchElementException.我真的不知道应该怎么做.我检查了路径和路径名是否正确.该文件必须在此处，并且在调试时也可以读取Scanner对象上的字段.那到底是什么问题呢?

The problem I am facing is when the java.util.Scanner is about to read the very first line. The program stops and gives me the NoSuchElementException. I can't really figure out what should be wrong. I checked that both path and pathname are made correctly. The file must be there, and I can read fields on the Scanner object as well when I debug. So what's the problem exactly?

有人暗示它可能认为文件中没有行.

Some was hinting at that it might think there are no lines in the file.

问题出现在while((line = scanner.next()) != null) {

@Override
public void run() {
    Scanner scanner = null;
    String filename = "", path = "";
    StringBuilder puBuilder, prBuilder, viBuilder;
    puBuilder = new StringBuilder();
    prBuilder = new StringBuilder();
    viBuilder = new StringBuilder();
    for(File f : files) {
        try {
            filename = f.getName();
            path = f.getAbsolutePath();
            path = path.replace(filename, "");
            filename = filename.replace(".cpp", "");
            scanner = new Scanner(new FileReader(f));
        } catch (FileNotFoundException ex) {
            System.out.println("FileNotFoundException: " + ex.getMessage());
        }

        String line;
        String tag;
        while((line = scanner.next()) != null) {
            line = line.trim();
            if(line.startsWith(PUBLIC)) {
                tag = PUBLIC;

推荐答案

罪魁祸首是:

while((line = scanner.next()) != null)

scanner.next()将如果没有更多可用令牌，则抛出NoSuchElementException .您可以改用hasNext方法:

scanner.next() will throw a NoSuchElementException if there are no more tokens available. You could use the hasNext method instead:

while(scanner.hasNext()) {
    String line = scanner.next();
    //etc.
}

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