Get the last line of a file in groovy

Question

Google doesn't give any great results for getting the last line of a file in groovy so I feel this question is necessary.

How does one get the last line of a file in groovy?

related: https://stackoverflow.com/a/22105812/1371329 – jaco0646 Jun 28 '19 at 16:39 — jaco0646, Jun 28 '19 at 16:39

score 1 · Answer 1 · edited Oct 03 '18 at 21:00

1

Here's what I ended up with:

    new File("/home/user/somefile.txt").eachLine {
        lastLine = it
    }

.eachLine iterates through each line of the text file and lastLine is set to the current iteration until eachLine finishes going through the file. Pretty straightforward.

edited Oct 03 '18 at 21:00

Community

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answered Sep 23 '16 at 13:56

Mike Sallese

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You don't need the `if(it != null){` surely? – tim_yates Sep 23 '16 at 14:05

Alexiy · Accepted Answer · 2016-09-24T05:47:08.410

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Get all lines, then get the last one:

def lines=new File("/home/user/somefile.txt").readLines()
def lastline=lines.get(lines.size()-1)

Or, if the file is dangerously large:

def last=new File('/home/user/somefile.txt').withReader {  r-> r.eachLine {it} }

which is almost identical to asker's answer.

edited Sep 24 '16 at 05:47

answered Sep 23 '16 at 15:38

Alexiy

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`lines[-1]` is more idiomatic groovy than the get/size-1 line – tim_yates Sep 23 '16 at 18:33
If the file is very large, this could exhaust your memory. – BalRog Sep 23 '16 at 20:23

score 0 · Answer 3 · answered Sep 24 '16 at 14:37

How does one get the last line of a file in groovy?

It depends on what you know about the file. If the lines in the file are fixed length then you could look at the file size, divide it by the length of each line and then use random file access to jump to the last line in the file and read it. That would be more efficient than reading the entire file. If you don't know the length of the lines then you are probably going to have to read the entire file and discard everything before the last line you read.

score 0 · Answer 4 · edited Aug 08 '23 at 14:04

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def fruitString = '"banana","apple","orange"'

def fruitArray = fruitString .split(',').collect{it as String}

log.info(fruitArray[0]) //banana

println(fruitArray[1]) //apple

edited Aug 08 '23 at 14:04

toyota Supra

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answered Aug 08 '23 at 13:12

J S

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Get the last line of a file in groovy

4 Answers4