Convert nested ArrayBuffer to nested Array in scala

The code below works for your specific test case. It converts nested ArrayBuffers that are the first element of the enclosing ArrayBuffer:

def convert(a: Any): Array[Any] = a match {
  case ArrayBuffer(inner @ ArrayBuffer(_*)) => Array(convert(inner))
  case ArrayBuffer(head @ ArrayBuffer(_*), tail @ _*) => (convert(head) +: tail).toArray
  case arr @ ArrayBuffer(_*) => arr.toArray
}

val result = convert(ArrayBuffer(ArrayBuffer(ArrayBuffer(ArrayBuffer(1, "b"), 5))))
// result is Array(Array(Array(Array(1, "b"), 5)))

Perhaps the above will help you come up with a more general solution.

I have created a generic function to convert arraybuffer to array.This takes care of nested arrayBuffers also

def convert(a: ArrayBuffer[Any]): Array[Any] = {

  val checkExistance = (x:ArrayBuffer[Any]) => x.zipWithIndex.collect{ case(x,y) if x.isInstanceOf[ArrayBuffer[Any]] => y}.toArray
  //filter(x => x.isInstanceOf[ArrayBuffer[Any]])
  val arr = checkExistance(a)
  for(i <- arr) {
    //if (a(i).isInstanceOf[ArrayBuffer[Any]]) {
    val m = a(i).asInstanceOf[ArrayBuffer[Any]]
    if(checkExistance(m).length > 0) {
      a.update(i,(convert(m)).toArray)
    }
    else {
      val n = m.toArray
      a.update(i,n)
    }
  }
  a.toArray
}