What does += do for list in Scala?

Question

What does the += do here ? Does it mean append to the list? If maxNodes = 16, Do the below lines mean that values 0 to 15 are stored in NodeList? Or is it 0 to 16?

var Nodelist = new ArrayBuffer[Int]()
for (i <- 0 until maxNodes) {     
          Nodelist += i  
 }

Answer 1

You're just appending the Integer value in variable i to the list. Why not try this in the REPL?

Answer 2

According to the Javadoc , += in ArrayBuffer is an "alias" for addOne() . So at the beginning NodeList is empty (I'd rather call it nodeList ). On the first go at the For loop, the integer 0 is added to NodeList . On the next go around, the integer 1 will be added to NodeList , and so and so forth. Since you used until rather than to , the iteration will stop one short of maxNodes .