Do I need to close both FileReader and BufferedReader

Question

I m reading a local file using a BufferedReader wrapped around a FileReader   BufferedReader reader   new BufferedReader new FileReader fileName       read the file     error handling snipped  reader close      Do I need to close   the FileReader as well  or will the wrapper handle that  I ve seen code where people do something like this   FileReader fReader   new FileReader fileName   BufferedReader bReader   new BufferedReader fReader      read the file     error handling snipped  bReader close    fReader close      This method is called from a servlet  and I d like to make sure I don t leave any handles open

User · Accepted Answer

no   BufferedReader close     closes the stream according to javadoc for BufferedReader and InputStreamReader  as well as  FileReader close     does

User · Answer

You Don t need to close the wrapped reader writer   If you ve taken a look at the docs  Reader close   Writer close     You ll see that in Reader close   it says      Closes the stream and releases any system resources associated with it    Which just says that it  releases any system resources associated with it   Even though it doesn t confirm   it gives you a nudge to start looking deeper  and if you go to Writer close   it only states that it closes itself   In such cases  we refer to OpenJDK to take a look at the source code   At BufferedWriter Line 265 you ll see out close    So it s not closing itself   It s something else  If you search the class for occurences of  out  you ll notice that in the constructor at Line 87 that out is the writer the class wraps where it calls another constructor and then assigning out parameter to it s own out variable    So   What about others  You can see similar code at BufferedReader Line 514  BufferedInputStream Line 468 and InputStreamReader Line 199  Others i don t know but this should be enough to assume that they do

User · Answer

After checking the source code  I found that for the example   FileReader fReader   new FileReader fileName   BufferedReader bReader   new BufferedReader fReader     the close   method on BufferedReader object would call the abstract close   method of Reader class which would ultimately call the implemented method in InputStreamReader class  which then closes the InputStream object   So  only bReader close   is sufficient

User · Answer

As others have pointed out  you only need to close the outer wrapper   BufferedReader reader   new BufferedReader new FileReader fileName      There is a very slim chance that this could leak a file handle if the BufferedReader constructor threw an exception  e g  OutOfMemoryError   If your app is in this state  how careful your clean up needs to be might depend on how critical it is that you don t deprive the OS of resources it might want to allocate to other programs   The Closeable interface can be used if a wrapper constructor is likely to fail in Java 5 or 6   Reader reader   new FileReader fileName   Closeable resource   reader  try     BufferedReader buffered   new BufferedReader reader     resource   buffered       TODO  input   finally     resource close        Java 7 code should use the try-with-resources pattern   try  Reader reader   new FileReader fileName       BufferedReader buffered   new BufferedReader reader          TODO  input

User · Answer

The source code for BufferedReader shows that the underlying is closed when you close the BufferedReader

User · Answer

I m late  but   BufferReader java   public BufferedReader Reader in      this in  defaultCharBufferSize             public void close   throws IOException       synchronized  lock            if  in    null              return          try               in close              finally               in   null              cb   null

User · Answer

According to BufferedReader source  in this case bReader close call fReader close so technically you do not have to call the latter

User · Answer

Starting from Java 7 you can use try-with-resources Statement  try  BufferedReader br   new BufferedReader new FileReader path          return br readLine        Because the BufferedReader instance is declared in a try-with-resource statement  it will be closed regardless of whether the try statement completes normally or abruptly  So you don t need to close it yourself in the finally statement   This is also the case with nested resource statements   This is the recomanded way to work with resources  see the documentation for more detailed information

User · Answer

You Only Need to close the bufferedReader i e reader close   and it will work fine

[java] Do I need to close() both FileReader and BufferedReader?

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