Unreported Exceptions and Closing Objects 1

[fatcodeguy]

Hi,

I have a program in which I do a lot of file reading, so I want to ensure i always close my FileInputStreams. To do this, I want to put the fis.close() statement in the finally{} block of my exception handling because the finally block is ALWAYS executed, whether an exception is caught or not (right?). So I do something like this

import java.io.*;
import java.lang.*;
import java.util.*;

public class Test{
    
    //main function
    public static void main (String args[]) {
           //vars
           String path = null;
           FileInputStream fis = null;
           File file = null;
         try{
             path = new String("V:\\sys\\crss-scrs\\20000\\3000\\800\\60\\veritas\\39788\\qa39788nssf.htm");
             file = new File(path);
             fis = new FileInputStream(file);
             int fileSize = (fis.available());
         }
         catch(IOException e) {System.out.println(e.getMessage());e.printStackTrace();}
         finally { fis.close();}
    }//end main
}//end class

But I get an error message

Test.java:29: unreported exception java.io.IOException; must be caught or declar
ed to be thrown
                    fis.close();
                             ^
1 error

Which makes sense, but I can't figure out how to make sure I ALWAYS close my file streams (the same thing happens with database connections conn.close()).

Can anybody help? Many thanks!

 

[sedj]

finally { 
  try {
    if (fis != null) 
          fis.close();
  } catch (IOException ioe) {
    System.err.println("Error closing file.");
    ioe.printStackTrace(System.err);
  }
}

--------------------------------------------------
Free Database Connection Pooling Software

http://www.primrose.org.uk

 

[fatcodeguy]

That seems redundant though. Suppose fis.close() fails in the try block of the finally block, then the input stream is still open. Or am I just not understanding this right?

Thanks

 

[sedj]

If your fis.close() operation fails then there is nothing you can do ...

So your choices are, leave your fis.close() operation in your original try block, which means you won;t even attempt to close the stream if some code above it fails on a read() operation ow whatever, or do as I have showed in the finally within another try block. There is not any other way of doing it.

--------------------------------------------------
Free Database Connection Pooling Software

http://www.primrose.org.uk

 

[fatcodeguy]

If your fis.close() operation fails then there is nothing you can do ..."

Good point...

Thanks!!