How to get the current index in for each Kotlin
AndroidFor LoopKotlinAndroid Problem Overview
How to get the index in a for each loop? I want to print numbers for every second iteration
For example
for (value in collection) {
if (iteration_no % 2) {
//do something
}
}
In java, we have the traditional for loop
for (int i = 0; i < collection.length; i++)
How to get the i
?
Android Solutions
Solution 1 - Android
In addition to the solutions provided by @Audi, there's also forEachIndexed
:
collection.forEachIndexed { index, element ->
// ...
}
Solution 2 - Android
Use indices
for (i in array.indices) {
print(array[i])
}
If you want value as well as index Use withIndex()
for ((index, value) in array.withIndex()) {
println("the element at $index is $value")
}
Reference: Control-flow in kotlin
Solution 3 - Android
Alternatively, you can use the withIndex
library function:
for ((index, value) in array.withIndex()) {
println("the element at $index is $value")
}
> Control Flow: if, when, for, while: > https://kotlinlang.org/docs/reference/control-flow.html
Solution 4 - Android
try this; for loop
for ((i, item) in arrayList.withIndex()) { }
Solution 5 - Android
forEachIndexed
in Android
Working Example of Iterate with Index
itemList.forEachIndexed{index, item ->
println("index = $index, item = $item ")
}
Update List using Index
itemList.forEachIndexed{ index, item -> item.isSelected= position==index}
Solution 6 - Android
It seems that what you are really looking for is filterIndexed
For example:
listOf("a", "b", "c", "d")
.filterIndexed { index, _ -> index % 2 != 0 }
.forEach { println(it) }
Result:
b
d
Solution 7 - Android
Ranges also lead to readable code in such situations:
(0 until collection.size step 2)
.map(collection::get)
.forEach(::println)
Solution 8 - Android
Please try this once.
yourList?.forEachIndexed { index, data ->
Log.d("TAG", "getIndex = " + index + " " + data);
}