---
title: "IntervalList"
description: "The list consisting of multiple intervals.

It is useful when you want to define your own dsl similar to the one used by LazyColumn where
list items can be defined via multiple item/items calls.

This interface is read only, in order to create a list you need to use [MutableIntervalList].


Note: this class is a part of [LazyLayout] harness that allows for building custom lazy layouts.
LazyLayout and all corresponding APIs are still under development and are subject to change."
type: "interface"
---

<div class='type'>Interface</div>


<a id='references'></a>

<div class='sourceset sourceset-common'>Common</div>



```kotlin
sealed interface IntervalList<out T>
```


The list consisting of multiple intervals.

It is useful when you want to define your own dsl similar to the one used by LazyColumn where
list items can be defined via multiple item/items calls.

This interface is read only, in order to create a list you need to use `MutableIntervalList`.


Note: this class is a part of `LazyLayout` harness that allows for building custom lazy layouts.
LazyLayout and all corresponding APIs are still under development and are subject to change.

#### Parameters

| | |
| --- | --- |
| T | type of values each interval contains in `Interval.value`. |



## Properties

<div class='sourceset sourceset-common'>Common</div>


```kotlin
val size: Int
```


The total amount of items in all the intervals.

Note that it is not the amount of intervals, but the sum of `Interval.size` for all the
intervals added into this list.



## Functions

```kotlin
operator fun get(index: Int): Interval<T>
```


Returns the interval containing the given `index`.


```kotlin
fun forEach(fromIndex: Int = 0, toIndex: Int = size - 1, block: (Interval<T>) -> Unit)
```


Iterates through all the intervals starting from the one containing `fromIndex` until the one
containing `toIndex`.

#### Parameters

| | |
| --- | --- |
| fromIndex | we will start iterating from the interval containing this index. |
| toIndex | the last interval we iterate through will contain this index. This index should be not smaller than `fromIndex`. |
| block | will be invoked on each interval within the defined indexes |