Closure Question

[Brian Mooney]

Hi,

Have been looking at Groovy recently and am interested in trying to learn it properly.
Was just trying some file manipulation using groovysh and I'm a little puzzled by something that I'm seeing.

I was simply trying to add line numbers to the contents of a file as per:

f = new File(System.getProperty("user.home") + "\\" + "testFile")
f.setText "1st Line\n2nd Line\nSome random text\nRandom Stuff\nLast line\nWell almost!!"
f.eachLine {e, i = 0 -> println (i + ": " + e); i++}

But when reviewing the output, I'm seeing:
1: 1st Line
2: 2nd Line
3: Some random text
4: Random Stuff
5: Last line
6: Well almost!!

If I update the code as per below (initialising the Integer i to 1 as opposed to 0):

f = new File(System.getProperty("user.home") + "\\" + "testFile")
f.setText "1st Line\n2nd Line\nSome random text\nRandom Stuff\nLast line\nWell almost!!"
f.eachLine {e, i = 1 -> println (i + ": " + e); i++}

I get the same output:
1: 1st Line
2: 2nd Line
3: Some random text
4: Random Stuff
5: Last line
6: Well almost!!

My question is why doesnt the first code block index the lines from zero?
To get the desired result, I have to edit the code as such:

f = new File(System.getProperty("user.home") + "\\" + "testFile")  
f.setText "1st Line\n2nd Line\nSome random text\nRandom Stuff\nLast line\nWell almost!!"  
def i=0
f.eachLine {println (i + ": " + it); i++}  

which results in:
0: 1st Line
1: 2nd Line
2: Some random text
3: Random Stuff
4: Last line
5: Well almost!!

This is of course very trivial but I'm more wondering where my understanding of what is happening is falling down as I would have expected the final result to be produced by the very first code block.

Appreciate any correspondance

[Jeanne Boyarsky]

Brian,
This does what you want. Passing the desired start index as a parameter prevents Groovy from using a default of 1 for the line number.

f.eachLine(0) {e, i -> println (i + ": " + e); }

The eachLine method is defining the second argument to be the line number. It ignores any requests you make of i. For example, if you change i++ to i+=2, you get the same behavior 1-6 as before because eachLine is helpfully setting i to the line number for you.

[Brian Mooney]

Indeed you're right. I was getting confused about the inputs for the eachLine() method.

Appreciate the response and help on the matter.

Regards,
Brian