我想得到子字符串

Currently I am using code like this

目前我正在使用这样的代码

    while (fileName.endsWith(".csv")) {
        fileName = fileName.substring(0, fileName.lastIndexOf(FILE_SUFFIX_CSV));
        if (fileName.trim().isEmpty()) {
            throw new IllegalArgumentException();
        }
    }

The above code works fine when user specifies extension in small letters(.csv),But windows accepts extensions case sensitive so he can give like .CsV ,.CSV etc. how can I alter above code ?

当用户用小写字母(.csv)指定扩展名时,上面的代码工作正常,但是windows接受区分大小写的扩展名,所以他可以给出类似.CsV,.CSV等。我怎样才能改变上面的代码?

Thanks in Advance

提前致谢

5 个解决方案

#1

why don't you turn it to lowercase?

你为什么不把它变成小写?

while (fileName.toLowerCase().endsWith(".csv")) {
    fileName = fileName.substring(0, fileName.toLowerCase().lastIndexOf(FILE_SUFFIX_CSV));
    if (fileName.trim().isEmpty()) {
        throw new IllegalArgumentException();
    }
}

#2

Late night regex solution:

深夜正则表达式解决方案:

Pattern pattern = Pattern.compile(".csv", Pattern.CASE_INSENSITIVE);
Matcher matcher = pattern.matcher(fileName);
while (matcher.find()) {
    fileName = fileName.substring(0, matcher.start());
    if (fileName.trim().isEmpty()) {
        throw new IllegalArgumentException();
    }
}

The Matcher will only find() once. It can then report its start position which you can use to substring the original file name.

匹配器只会找到()一次。然后,它可以报告其起始位置,您可以使用该位置对原始文件名进行子串。

#3

You can try this way

你可以试试这种方式

 int lastIndexOfDot=fileName.lastIndexOf("\\.");
 String fileExtension=fileName.substring(lastIndexOfDot+1,fileName.length()); 
 while(fileExtension.equalsIgnoreCase(".csv")){

 }

while(fileName.toUpperCase().endsWith(".CSV"){}

#4

Please convert to lowercase and then compare.

请转换为小写然后进行比较。

  while (fileName.toLowerCase().endsWith(".csv")) {
        fileName = fileName.toLowerCase().substring(0, fileName.toLowerCase().lastIndexOf(FILE_SUFFIX_CSV));
        if (fileName.toLowerCase().trim().isEmpty()) {
            throw new IllegalArgumentException();
        }
    }

#5

You can convert both to uppercase.

您可以将两者都转换为大写。

So change this line

所以改变这一行

fileName = fileName.substring(0, fileName.lastIndexOf(FILE_SUFFIX_CSV));

fileName = fileName.toUpperCase().substring(0, fileName.lastIndexOf(FILE_SUFFIX_CSV.toUpperCase()));

#1