File check permission

Question

I'm trying to check permission of the given file using the following code snippet.

public static void main(String[] args) {
    try{
        FilePermission fp = new FilePermission("E:/test.txt", "read");
        AccessController.checkPermission(fp);
        System.out.println("Ok to open socket");
    } catch (AccessControlException ace) {
        System.out.println(ace);
    }

So when I run it, it gives me following exception:

java.security.AccessControlException: access denied ("java.io.FilePermission" "E:/test.txt" "read")

All the rights are enable on file but it throws me access denied exception.

Answer 1

Use the following snippet to check if you can read the file:

boolean canRead = new java.io.File("E:/test.txt").canRead();

File.canRead checks if the SecurityManager (if there is any) allows to read the file and if you have read rights in the file system.

Using AccessController.checkPermission(fp) will only not throw an exception if there is a security context which implies the permission. This is not the case when you simply start a Java app as in your example.