How can I use a keyword "break" in foreach ? In J...

# getting-started

[Oleh Ponomarenko]

How can I use a keyword "break" in foreach ?
In Java I have this

for (it in this.list) {
                if (it == example) {
                    //do smth
                    break
                }
            }

In Kotlin I use:

this.list.foreach{
    if(it==example) //do smth
}

I can't use "break" in foreach. I get an error: "Break & continue is only allowed inside a loop".

[marstran]

Try return@foreach

[Oleh Ponomarenko]

It is just skip in preset case
http://prntscr.com/mk22v2

[Oleh Ponomarenko]

I have found the solution 🙂
I can use a keyword "first".
Now my code is:
this.list.first { it == example }.apply { this.amount = +1 }

[marstran]

Ah, right. To simulate a break, you have to label an outer scope. You can use run to make that scope.

run {
  listOf(1,2,3,4,5).forEach {
    if (it == 3) return@run
    print(it)     
  }
}

[marstran]

Check this page: https://kotlinlang.org/docs/reference/returns.html

[Oleh Ponomarenko]

ok, thanks, I 'll keep in mind your solution too)

[Oleh Ponomarenko]

I saw that page but I have not found any solution for my case

[marstran]

It's the last example with the run loop@ label.

[Oleh Ponomarenko]

You are right, I just have not noticed it.

[Uzi Landsmann]

A different solution is to use tail recursion instead

[Jake]

I believe you could do something like:

this.list.filter{ it == example }.apply { ... }

to do the same thing.

[Oleh Ponomarenko]

@Jake I think this filter will be going through the whole list and will not stop when some match is found

[Oleh Ponomarenko]

But I need just get an item from the "Set"

[marstran]

So you want to find the first item that matches some criteria? In that case, you should use find.

[aarjav]

Also this isn't for your case but in general, another common case for breaking out of loop is to stop iterating once a certain condition is met. For that there's takeWhile method

[Shawn]

Am I missing something? Is there something that makes a regular for (item in list) foreach loop not acceptable now?

[Shawn]

Like, sure, first() or find() is more appropriate for this particular use case but nothing wrong with using regular ol’ loops in Kotlin when you need to

[aarjav]

It may already be part of a bigger chain

[Oleh Ponomarenko]

it is acceptable, but I was looking more short form of code)

[Shawn]

using forEach at the end of a functional chain is fine, but is still really only geared towards cases where you’re okay with applying your transform to every element of whatever iterable you’re working on

[SOFe]

Actually your first code snippet for (it in this.list) it is Kotlin too... In both Java and Kotlin you still have forEach too...