选取一个 Traversable 对象的前N个元素

解决方案：

1、take

2、takeWhile

package main

object Test {

  def main(args: Array[String]): Unit = {

    val t1 = Traversable(1 to 10: _*);
    println(t1);
    //List(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)


    val take = t1.take(5);
    println(take);
    //List(1, 2, 3, 4, 5)

    val take2 = t1 take (3);
    println(take2);
    //List(1, 2, 3)

    val take3 = t1 take 3
    println(take3);
    //List(1, 2, 3)


　　 println( 
　　　　　　Traversable(1, 3, 5, 2, 4, 6).take(3) 
　　 );
　　 //List(1, 3, 5)

    
    
    val takeWhile1 = t1.takeWhile(_ > 6); //t1.takeWhile(x => x > 6)
    println(takeWhile1);
    //List()

    val takeWhile2 = t1.takeWhile(_ < 6);
    println(takeWhile2);
    //List(1, 2, 3, 4, 5)

    

    println(
      Traversable(1 to 10: _*)
        .takeWhile(_ > 6)
    )
    //List()

    println(
      Traversable(7, 8, 9, 1, 2, 3, 4, 5, 6)
        .takeWhile(_ > 6)
    )
    //List(7, 8, 9)

    println(
      Traversable(7, 8, 1, 2, 3, 4, 5, 6, 9)
        .takeWhile(x => x > 6)
    )
    //List(7, 8)


    //def takeWhile(p : scala.Function1[A, scala.Boolean]) : Repr
    /**
      * takeWhile()是根据断言从头开始一直选择元素，直到某个元素不满足这个断言为止。
      **/
  }
}