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Check if filename is validTag(s): IO


This HowTo will only check if a given filename is valid according to the OS rules.

You still need to handle other failures when actually creating the file (e.g. insufficient permissions, lack of drive space, security restrictions). 

import java.io.File;
import java.io.IOException;

public class FileUtils {
  public static boolean isFilenameValid(String file) {
    File f = new File(file);
    try {
       f.getCanonicalPath();
       return true;
    }
    catch (IOException e) {
       return false;
    }
  }

  public static void main(String args[]) throws Exception {
    // true
    System.out.println(FileUtils.isFilenameValid("well.txt"));
    System.out.println(FileUtils.isFilenameValid("well well.txt"));
    System.out.println(FileUtils.isFilenameValid(""));

    //false
    System.out.println(FileUtils.isFilenameValid("test.T*T"));
    System.out.println(FileUtils.isFilenameValid("test|.TXT"));
    System.out.println(FileUtils.isFilenameValid("te?st.TXT"));
    System.out.println(FileUtils.isFilenameValid("con.TXT")); // windows
    System.out.println(FileUtils.isFilenameValid("prn.TXT")); // windows
    }
  }
Related HowTo : Sanitize a valid Windows filename.