[英]java FilenameFilter regex (look ahead)
I am trying to filter files using FilenameFilter to grep files files in a directory. 我正在尝试使用FilenameFilter过滤文件以grep目录中的文件文件。
% ls -1
DirFilter.class
DirList.class
DirList.java
doctors.txt
node.l
rels.l
I am trying to filter node.l
and rels.l
. 我试图过滤node.l
和rels.l
Filter should succeed if and only if both files are present. 当且仅当两个文件都存在时,过滤器才会成功。
I tried my regex on debuggex.com and it seems to work as expected : http://www.debuggex.com/embed/CZgVeUE2iWsNfRNG 我在debuggex.com上尝试了我的正则表达式,它似乎按预期工作: http : //www.debuggex.com/embed/CZgVeUE2iWsNfRNG
my regex : (?s)node.l.?(?=(rels.l))
我的正则表达式:( (?s)node.l.?(?=(rels.l))
but when I run it through DirList.java
filter it doesn't work.. 但是当我通过DirList.java
过滤器运行它时它不起作用..
% java DirList "(?s)node.l.?(?=(rels.l))"
<no-output>
Now I am using DirList.java from Thinking in Java http://www.cs.odu.edu/~cs476/tijava2/c10/DirList.java 现在我使用Thinking in Java中的DirList.java http://www.cs.odu.edu/~cs476/tijava2/c10/DirList.java
Any ideas? 有任何想法吗?
DirList
is evaluating your regex against each file name separately, not as a single \\n
delimited directory listing string as returned by ls
. DirList
分别针对每个文件名评估您的正则表达式,而不是ls
返回的单个\\n
分隔目录列表字符串。 Your regex will never match under those conditions since it never sees more than one file name at a time. 你的正则表达式永远不会在这些条件下匹配,因为它一次看不到多个文件名。
FilenameFilter works for single file not for groups of files so regex will be applied only to that single file. FilenameFilter适用于单个文件而不适用于文件组,因此正则表达式仅适用于该单个文件。 Instead of regex try maybe this way: 而不是正则表达式尝试可能这样:
node.l
check if new File(currentDir+"/rels.l").exists()
. 如果是node.l
请检查是否有new File(currentDir+"/rels.l").exists()
。 rels.l
check if new File(currentDir+"/node.l").exists()
. 如果它是rels.l
检查是否有new File(currentDir+"/node.l").exists()
。
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