Use regular expressions to filter application files in a directory name, File and the FilenameFilter

FilenameFilter achieved with DirFilter, capable of expression to filter the file name in the directory by positive;

It may also be implemented in other ways other filters, similar to the filter size, type, etc.!

class DirFilter implements FilenameFilter{

 

    private Pattern pattern;

    public DirFilter(String regex) {

        pattern = Pattern.compile(regex);

    }

    @Override

    public boolean accept(File dir, String name) {

        return pattern.matcher(name).matches();

    }

}

 

 

 

• Get all the files:

Regular expression: "[\\ s \\ S] *" indicates the character of any length:

    @Test 

    public  void DirFileter () { 

        File path = new new File ( "." ); 

        String [] List; 

        List = path.list ( new new DirFilter ( "[S \\ \\ S] *" )); 

        // List path.list = (); // no way to obtain a regular expression 

        Arrays.sort (List, String.CASE_INSENSITIVE_ORDER); 

        for (String dirItem: List) { 

            System.out.println (dirItem); 

        } 

    }

result:

• Obtain a specific file: Regular expression: "[az] *"

 

    @Test

    public void DirFileter2(){

        File path = new File(".");

        String[] list;

        list = path.list(new DirFilter("[a-z]*"));

        Arrays.sort(list,String.CASE_INSENSITIVE_ORDER);

        for(String dirItem : list){

            System.out.println(dirItem);

        }

    }

 

Results: Get all lowercase letters in file names