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  Fastest way to load a file into a ArrayList?  (Read 503 times)
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Offline Tyecon

Senior Newbie





« Posted 2013-03-28 03:05:18 »

I'm trying to load a 3.4MB file into a collection of some sort, where calling index 5 would return line 5 of the file. Also clean up such as removing whitespace and empty lines. My current code is a buffered reader that's throwing everything into a single string, which then later gets split into the ArrayList. The first thing I tried (Scanner line by line) made it take like 10 minutes to load; Now it's around 2-5.

What's better for reading a file that's going to be parsed? Scanner, BufferedReader, ByteReader?
What's the best way to turn a large string into a collection?

Please have a baggy ready before looking at my code.
Offline Nate

« JGO Bitwise Duke »


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« Reply #1 - Posted 2013-03-28 03:34:45 »

BufferedReader reads lines. Read each line and put it in your list. It should complete 3.4MB in about 1 second.

Offline Danny02
« Reply #2 - Posted 2013-03-28 09:24:20 »

if you want to read all lines of a file anyway, then there is a shortcut now with Java7.
1  
2  
  Path file = Paths.get("./blubb.txt");
  List<String> lines = Files.readAllLines(file, Charset.defaultCharset());


with this you lose all the boilerplate stream/reader and try/catch code
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