Create a read-only file

Question

I was wondering wether it is possible to create or simulate a file with a content set at creation and the assurance that nobody can ever change the file. If possible, can I

Answer 1

Setting a file to read only is not going to make it so no one can ever change it. It takes about 3 seconds to unset the read only flag. The file can then be opened in a hex editor or other program that can handle the file type and changes can be made.

Answer 2

In this case simply you have to create a file using File class after that by reference you have to call setReadOnly() method.

    File f=new File("abc.txt");
    f.setReadOnly();

Answer 3

If you simply just need to create a Read-Only file, then won't the code below be sufficient? Unless I am missing something from your question:

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

public class FileAttributesDemo {

  public static void main(String[] args) throws IOException {
    // Create a new file, by default canWrite=true, readonly=false
    File file = new File("test.txt");
    if (file.exists()) {
      file.delete();
    }
    file.createNewFile();
    System.out.println("Before. canWrite?" + file.canWrite());

    // set to read-only, atau canWrite = false */
    file.setWritable(false);
    System.out.println("After. canWrite?" + file.canWrite());
  }
}

Answer 4

Read-only way can be useful altough it is not impossible to change or crack.So if you can not create an unreachable file then you can convert its contents to not understandable thanks to some kind of Encryption algorithms.For example AES may be so usefull.

Answer 5

Try:

• file.setReadOnly()
• Runtime.getRuntime().exec("attrib " + "" + file.getAbsolutePath() + "" + " +R"); //(works on Windows)

Answer 6

yes we can make read only file in java using setReadOnly() method.

After using this method, you will not be able to write or edit into the file.

import java.io.File;

public class FileReadOnly {
  public static void main(String[] args) {
    File file = new File("c:/file.txt");
    file.setReadOnly();
    System.out.println("File is in read only mode");
    }
}

or in this way also.

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

public class FileAttributesDemo {

  public static void main(String[] args) throws IOException {
    // Create a new file, by default canWrite=true, readonly=false
    File file = new File("test.txt");
    if (file.exists()) {
      file.delete();
    }
    file.createNewFile();
    System.out.println("Before. canWrite?" + file.canWrite());

    // set to read-only, atau canWrite = false */
    file.setWritable(false);
    System.out.println("After. canWrite?" + file.canWrite());
  }
}