# 
## Overview

We can use the **`contains` method** to check if the `SplayTreeSet` contains an element.

> **Note**: A **`SplayTreeSet`** is a set of objects that can be ordered relative to each other.

## Syntax 

```dart
bool contains (Object element)
```

## Parameter
The `contains` method takes the element that is to be checked as a parameter.

## Return value
This method returns `true` if the passed element is present in the `SplayTreeSet`. Otherwise, `false` is returned.



## Example

The code written below demonstrates how we can use the `contains` method to check if the `SplayTreeSet` contains an element:



import 'dart:collection';
void main() {
  //create a new SplayTreeSet which can have int type elements
  SplayTreeSet set = new SplayTreeSet<int>((a,b) =>  b.compareTo(a));

  // add five elements to the set
  set.add(5);
  set.add(4);
  set.add(3);
  set.add(2);
  set.add(1);

  print('The set is $set');

  // check if element contians 5
  print('set.contains(5) : ${set.contains(5)}');

  // check if element contians 10
  print('set.contains(10) : ${set.contains(10)}');
}

## Explanation 

* **Line 1**: We import the `collection` library. 

* **Line 4**: We create a new `SplayTreeSet` object with the name `set`. We pass a `compare` function as an argument. This function is used for maintaining the order of the `set` elements. In our case, the `compare` function orders the elements in descending order.

* **Lines 7 to 11**: We add five new elements to the `set`. Now, the set is `{5,4,3,2,1}`.

* **Line 16**: We use the `contains` method to check if the element `5` is present in the `set`. The element is present so `true` is returned.

* **Line 19**: We use the `contains` method to check if the element `10` is present in the `set`. The element is not present so `false` is returned.

How to check if the SplayTreeSet contains an element in Dart

Use the `contains` method to check if a SplayTreeSet contains an element, returning true or false.