Replacing string in a file with another string

Question

What is the fastest way to do a search and replace on a string in an existing file using Java?

Let's say I have this:

// This references an existing file 
File file = ...

The file in question looks like this:

The Green Dog is furry.
It likes to run in the Green Grass.
Green is its favorite color.

How would I go about replacing the String "Green" with "Blue" and having that file re-saved with the new color?

Update: I've thought about this a little more and perhaps the best and fastest way is to just read the contents of the file into a string (using something like FileUtils) and then just doing a replace and re-writing to the file?

Not the same answer, but close stackoverflow.com/questions/3939561/… — zengr
– zengr, Commented Feb 22, 2011 at 1:02

Community · Accepted Answer · 2017-05-23 12:20:40Z

4

Have a look at Retrieving and Replacing number in text file which is pretty much the same.

Edit: Regarding your update, I would just use BufferedReader and BufferedWriter and leave it to the JVM to optimise reads/writes, i.e. I would do the replacements in a streaming fashion. Your suggested solution of reading to memory could be a bit faster - but I wouldn't read everything in memory (makes approach not scalable) unless there's a very good reason.

edited May 23, 2017 at 12:20

CommunityBot

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answered Feb 22, 2011 at 0:56

Lucas Zamboulis

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