Scala get first element of ArrayBuffer which satisfies condition

Question

I have a var of type ArrayBuffer.

var selected = new ArrayBuffer[Component](0)

I would like to extract from it the first element which satisfies a given condition.

var res = selected.filter(_.node == neighbour)(0)

I want something like the line above, but in case no element satisfies that condition, I want res to be null. Instead, the code is throwing an error.

How can I get the first element satisfying the condition or null?

knutwalker · Accepted Answer · 2015-12-21 18:16:59Z

8

First, use find instead of filter which will return the first one on an Option. Then use orNull to get the value or null if it is missing:

val res = selected.find(_.node == neighbour).orNull

Or you could use filter, headOption, and orNull

val res = selected.filter(_.node == neighbour).headOption.orNull

As a kind of mandatory note when dealing with null: Using Option instead of null is the scala idiomatic and recommended way.

answered Dec 21, 2015 at 18:16

knutwalker

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