Closing a Java FileInputStream

Question

Alright, I have been doing the following (variable names have been changed):

 FileInputStream fis = null; try {     fis = new FileInputStream(file);      ... process ...  } catch (IOException e) {     ... handle error ... } finally {     if (fis != null)         fis.close(); }  

Recently, I started using FindBugs, which suggests that I am not properly closing streams. I decide to see if there's anything that can be done with a finally{} block, and then I see, oh yeah, close() can throw IOException. What are people supposed to do here? The Java libraries throw too many checked exceptions.

Answer 1

For Java 7 and above try-with-resources should be used:

try (InputStream in = new FileInputStream(file)) {   // TODO: work } catch (IOException e) {   // TODO: handle error } 

If you're stuck on Java 6 or below...

This pattern avoids mucking around with null:

    try {         InputStream in = new FileInputStream(file);         try {             // TODO: work         } finally {             in.close();         }     } catch (IOException e) {         // TODO: error handling     } 

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For a more detail on how to effectively deal with close, read this blog post: Java: how not to make a mess of stream handling. It has more sample code, more depth and covers the pitfalls of wrapping close in a catch block.

Answer 2

Something like the following should do it, up to you whether you throw or swallow the IOException on attempting to close the stream.

FileInputStream fis = null; try {     fis = new FileInputStream(file);      ... process ...   } catch (IOException e) {     ... blah blah blah ... } finally {     try     {         if (fis != null)             fis.close();     }     catch (IOException e)     {     } }