error unreported exception when use BufferedInputStream

Question

I am trying to copy files using BufferedInputStream, and this error occurred when compile:

BufferedByteStreamCopy2.java:22: error: unreported exception IOException; must be caught or declared to be thrown bin.close(); ^ BufferedByteStreamCopy2.java:24: error: unreported exception IOException; must be caught or declared to be thrown bout.close(); ^

Could you help me to explain this? How can I modify the code? Many thanks!

import java.io.*;
public class BufferedByteStreamCopy2 {
  public static void main(String[] args) {
    BufferedInputStream bin = null;
    BufferedOutputStream bout = null;
  try {
    FileInputStream fin = new FileInputStream(args[0]);
    bin = new BufferedInputStream(fin);
    FileOutputStream fout = new FileOutputStream(args[1]);
    bout = new BufferedOutputStream(fout);
    int c;
    while ((c = bin.read()) != -1)
    bout.write(c);
 } catch (ArrayIndexOutOfBoundsException e) {
  System.out.println("Not enough parameter.");
 } catch (FileNotFoundException e) {
  System.out.println("Could not open the file:" + args[0]);
 } catch (Exception e) {
  System.out.println("ERROR copying file");
 } finally {
   if (bin != null)
      bin.close();
   if (bout != null)
      bout.close();
 }

} }

The code you've provided compiles fine. Given the name of your public class and the filename reported in the error, are you sure this isn't just a matter of having two copies of your source code - one working and one broken? — Jon Skeet
– Jon Skeet, Commented Mar 29, 2014 at 7:57

Peter Lawrey · Accepted Answer · 2014-03-29 11:05:04Z

0

try/catch will catch an Exception but this doesn't apply to an exception thrown in a finally block. You need a try catch for the close() in there as well.

Note: copying a byte at a time is pretty inefficient, I assume this is just an exercise. As @EJP point out there is more read() and write() methods.

edited Mar 29, 2014 at 11:05

answered Mar 29, 2014 at 7:56

Peter Lawrey

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2 Comments

user3474606 Over a year ago

Thank you Peter! Sorry for the confusion..Here is the edited post with ButteredByteStreamCopy2Java. Exactly like you said it is an exercise. Although I don't really know a more efficient way.

user207421 Over a year ago

@user3474606 You had it right the first time, with a try/catch block inside the exception handler. The issue of one byte at a time isn't major given you're using buffered streams, but there are other read() methods. Look them up.

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