正则表达式与文件名末尾不匹配

Question

I need to filter out the files in a directory that end with "_done".
The directory contains three .txt files, namely format1.txt , format2.txt and format2_done.txt that needs to be filtered out.

The following sample correctly lists all the files:

System.out.println("all files: ");
String[] files = folder.list();
for (String item : files) {
    System.out.println(item);
}

Output:

all files: 
format1.txt
format2.txt
format2_done.txt

But the following sample:

System.out.println("filtered: ");
String[] filteredFiles = folder.list((File folder, String name) 
                         -> {return !(name.matches("_done.txt>"));});

for (String item : filteredFiles) {
    System.out.println(item);
}

produces the same output and doesn't filter anything:

filtered: 
format1.txt
format2.txt
format2_done.txt

What am I doing wrong?

Answer 1

Try to use this regex instead .*_done\\\\.txt$ like this :

String[] filteredFiles = folder.list((File folder, String name)
        -> !name.matches(".*_done\\.txt$")
);

details :

• .* zero or more character
• followed by _done\\\\.txt , note that you should to escape the dot with \\\\
• $ end anchor

Or you can just use String::endsWith :

String[] filteredFiles = folder.list((File folder, String name)
        -> !name.endsWith("_done.txt")
);