Assign value to variable only if is not null - Kotlin

Is there a clean way in Kotlin to assign a value to a variable only if the value is not null?

My example is:

if(x != null)
y = x

I found a solution like

y = x? : return

but I don't understand if this does what I want and how this operator works.

The operator is called Elvis Operator. It evaluates if `x` is not null and if that's true, assigns `x` to `y`. If it is null, it evaluates the statement after the question mark, returning immediately and therefore leaving `y` untouched.

Another solution if You don't want to return from function just yet:

x?.let{ y = it }

Which checks if `x` is non-null then passes it as the only parameter to the lambda block.

This is also a safe call in case your `x` is a `var`.

Your code is the exact same but with less writing as:

if(x != null)
y = x
else
return

When using the Elvis Operator it shortens the if else statement to:

y=x ?: return
If the left side is true (x is not null) then y will be assigned, else the right side will be executed.

For those searching and want a solution that does **not** immediately return. You can hold your nose and do this:

`y = x ?: y`

As a good programmer I shudder to assign a variable to itself just to satisfy syntax. But that's kotlin for you! Those designers thought of everything!