如何简化这个'for'循环？

Question

val xsa = List(1,2,3)
val xsb = List(1,2,3)
for (i <- 0 until xsa.size) {
    val a = xsa(i)
    val b = xsb(i)
    println(a + "_" + b)
}

我想简化长度等于'List或Array.我希望这样做:

for (a <- xsa; b <- xsb)
    println(a + "_" + b)

但为什么它只迭代xsb一次？

Answer 1

for ((a,b) <- xsa zip xsb)
  println(a + "_" + b)

Answer 2

(xsa, xsb).zipped foreach ((a, b) => println (a + "_" + b))

要么

(xsa, xsb).zipped map (_ + "_" + _) foreach println