# Server Side Kotlin-19

  #### List Operations
If the list size is less than the specified index, an exception is thrown.  However two functions can avoid such exception.   
getOrElse():It calculate the default value to return if the index is absent in the collection.  
getOrNull(): returns null as the default value.  

```   
val numbers = listOf(11, 22, 33, 44)
println(numbers.getOrNull(5))             // null
println(numbers.getOrElse(5, {it}))        // 5    
```   
output:-   
  null  
5    

subList() function gives elements  as a list from a give range.  
```  
val numbers = (10..23).toList()
println(numbers.subList(2, 4))  
```  
outuput:  
[12, 13]        

 Position of an element can be get by  indexOf() and lastIndexOf(). They return the first and the last position of an element . If  elements is not found , both functions return -1.     
```
val numbers = listOf(11, 22, 33, 44, 25, 56)
println(numbers.indexOf(3))
println(numbers.lastIndexOf(3))   
```   
ouput:-  
-1  

-1