Question

I have some questions regarding java finalization.
For example I have one class FileHelper and this class is associated with reading file,writing file,etc.
Now my question is, I have one method writeFile() in FileHelper class.Now If I want to close that file
should I override the finalize() method and close the file or can I close the file inside the writeFile() method itself? Which is the right way to do? I have declared my File variable as a member variable. If overriding is a bad idea, then why do we want to override finalize() method? which scenario? I have read many articles,where they are saying to close system resources such as file,font etc..

Answer 1

The best practice is to close the file as soon as possible. If you have static method in FileHelper (assuming that your Helper is a bunch of static “helper” methods) I would close the file inside

static void writeFile(String fileName, String text) { // Exception 
 // Open file here 
 // write text
 // close it
}

The purpose of overriding finalize is release the unmanaged resources e.g. files in case someone forget to do it. If someone use your helper this way

 FileHelper fileHelper = new FileHelper(file);
 fileHelper.writeFile(text);
 // forgot to fileHelper.close(); 

and you have overridden the finalize and call close() inside when GC runs the file will be closed. The problems:

• As I mention earlier file should be closed as soon as possible (but not sooner 😉 )
• It’s indeterministic (No body knows when GC will start)
• This should be used only to prevent the case when the caller forgets to close the file