检测文件中的行尾

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英文:

Detect the end of line in file

问题

以下是翻译好的部分:

我正在尝试读取一个 txt 文件并显示文件元素。我希望将元素显示在同一行,以实现单行换行。但是,在文件中的新行开始时,要多给一个新行。txt 文件内容如下:

《星际穿越》 % 克里斯托弗·诺兰 % 2014 % PG-13

《盗梦空间》 % 克里斯托弗·诺兰 % 2010 % PG-13

《复仇者联盟:终局之战》 % 卢素斯兄弟 % 2019 % PG-13

这里,% 是分隔符。我目前的做法是:

File file_path = new File("film.txt");
try {
    Scanner file_input = new Scanner(file_path);
    file_input.useDelimiter("%");
    for(new_book=1; file_input.hasNext(); new_book++) {
        String book_item = file_input.next().trim();
        System.out.println(book_item);
        if(new_book%4==0){
            System.out.println();
        }
    }
    file_input.close();
} 
catch (FileNotFoundException e) {
    System.out.println("文件未找到");
}

它给出的结果是:

星际穿越 
克里斯托弗·诺兰
2014
PG-13
盗梦空间 
克里斯托弗·诺兰
2010
PG-13
复仇者联盟:终局之战 
卢素斯兄弟
2019
PG-13

我希望得到的结果是:

星际穿越 
克里斯托弗·诺兰
2014
PG-13

盗梦空间 
克里斯托弗·诺兰
2010
PG-13

我注意到的问题是,在行末尾索引不起作用,即如果我打印 new_book,则 new_book 的值不会显示在第一个和第二个 PG-13 中,但会显示在最后一个 PG-13 中。

我对文件中的这一行感到困惑。非常欢迎各种建议!请注意,我不困惑于语法错误,而是困惑于逻辑和文件阅读过程的处理方式。

英文:

I am trying to read a txt file and display the file elements. I want to display elements in same line to give a single line break. But, give extra new line when new line in file starts. The txt file is:

> Interstellar % Christopher Nolan % 2014 % PG-13
>
> Inception % Christopher Nolan % 2010 % PG-13
>
> Endgame % Russo Brothers % 2019 % PG-13

Here, % is delimeter. What I have done so far:

File file_path = new File("film.txt");
try {
    Scanner file_input = new Scanner(file_path);
    file_input.useDelimiter("%");
    for(new_book=1; file_input.hasNext(); new_book++) {
        String book_item = file_input.next().trim();
        System.out.println(book_item);
        if(new_book%4==0){
            System.out.println();
        }
    }
    file_input.close();
} 
catch (FileNotFoundException e) {
    System.out.println("File not found");
}

What it gives:

Interstellar 
Christopher Nolan
2014
PG-13
Inception 

Christopher Nolan
2010
PG-13
Endgame 
Russo Brothers

2019 
PG-13

What I want is:

Interstellar 
Christopher Nolan
2014
PG-13

Inception 
Christopher Nolan
2010
PG-13

What I have noticed is, at the end of line indexing is not working i.e, if I print new_book then, new_book value is not shown in first and second PG-13, but shows in last PG-13.

I am confused with this line in file. Every suggestion is appreciated!!! Also, note that I am not confuse with syntactical error. But, with the logic and how file reading process is done.

答案1

得分: 1

file_input = new Scanner(file);
while(file_input.hasNextLine()){
String st = file_input.nextLine();
String[] s = st.split("%");
if(s.length > 1)
System.out.println(s[0] + "\n" + s[1] + "\n" + s[2] + "\n" + s[3] + "\n");
}
file_input.close();

英文:

You can try to read the line and then split it

file_input = new Scanner(file);
while(file_input.hasNextLine()){
    String st = file_input.nextLine();
    String[] s = st.split("%");
    if(s.length > 1)
        System.out.println(s[0] + "\n" + s[1] + "\n" + s[2] + "\n" + s[3] + "\n");
}
file_input.close();

答案2

得分: 1

我使用了scanner.nextLine()函数一次性读取整行。然后,我使用String.split("%")将行字符串拆分为字符串列表。最后,我在输出之前对每个字符串使用了String.trim()以去除前导和尾随空白。

File file_path = new File("film.txt");
try {
    Scanner file_input = new Scanner(file_path);
    while(file_input.hasNextLine()){
        String line = file_input.nextLine();
        String[] items = line.split("%");

        for(String item: items)
            System.out.println(item.trim());
        
        System.out.println();

    }
} catch (FileNotFoundException e) {
    e.printStackTrace();
}
英文:

I used the scanner.nextLine() function to read the entire line at once. Then I split the line string into a list of strings with String.split("%"). Finally I used String.trim() on each String before outputting to remove leading and trailling whitespace.

File file_path = new File("film.txt");
try {
    Scanner file_input = new Scanner(file_path);
    while(file_input.hasNextLine()){
        String line = file_input.nextLine();
        String[] items = line.split("%");

        for(String item: items)
            System.out.println(item.trim());
        
        System.out.println();

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

答案3

得分: 1

问题在于换行符号没有被视为分隔符,因此第四个标记被读取为 PG-13<NEWLINE>Inception - 内部嵌套了一个换行符。你有以下选项:

将换行符添加为可能的分隔符:

Scanner file_input = new Scanner(file_path);
file_input.useDelimiter("%|\n");

或者在输入文件的每一行末尾添加 %

> Interstellar % Christopher Nolan % 2014 % PG-13 %<br>
> Inception % Christopher Nolan % 2010 % PG-13 %

或者改变读取文件的方式,逐行读取并按 % 进行分割(参见其他人的回答)。

英文:

The problem is that the line break is not considered as a delimiter so the 4th token is read as PG-13&lt;NEWLINE&gt;Inception - with a line break embedded inside. Your options are:

Add line break as a possible delimiter:

Scanner file_input = new Scanner(file_path);
file_input.useDelimiter(&quot;%|\n&quot;);

Or add % at the end of every line in the input file:

> Interstellar % Christopher Nolan % 2014 % PG-13 %<br>
> Inception % Christopher Nolan % 2010 % PG-13 %

Or change the way the file is read to reading line by line and splitting on % (see answers by others)

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  • 本文由 发表于 2020年4月8日 19:53:15
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