Java Processing Large files

For the contents of a small file, when processing, you can simply load it all into memory, and then processing:

        /**          * Read all the contents of         the file into memory */         try  {            list<String> list = Fileutils.readlines (new  File (Filederec), charsets.utf_8);            System.out.println (List.get (0));         Catch (IOException e) {            e.printstacktrace ();        }

However, when working with large files (GB level), simply loading them into memory can cause memory overflow. Therefore, it is usually handled in the following ways:

        /*** java.util.* file stream processing*/FileInputStream fi=NULL; Scanner SC=NULL; Try{fi=NewFileInputStream (NewFile (Filederec)); SC=NewScanner (FI, "UTF-8"); if(Sc.hasnextline ()) {System.out.println (Sc.nextline ()); }        } Catch(Exception e) {}finally {            if(Fi! =NULL) {                Try{fi.close (); } Catch(IOException e) {//TODO auto-generated Catch blockE.printstacktrace (); }            }            if(SC! =NULL) {sc.close (); }        }

You can also use packages that are used by third parties:

        /*** Stream processing provided by Apache-commons-io*/Lineiterator Li=NULL; Try{li= Fileutils.lineiterator (NewFile (Filederec), "UTF-8"); if(Li.hasnext ()) {System.out.println (Li.next ()); }        } Catch(IOException e) {//TODO auto-generated Catch blockE.printstacktrace (); } finally{lineiterator.closequietly (LI); }

Java Processing Large files