一、獲取第一個元素
1.take()
scala> "hello".take(1)
res12: String = h
2.索引法
因爲字符串的本質是字符數組
scala> "hello"(0)
res13: Char = h
3.字符串截取
scala> "hello".substring(0,1)
res15: String = h
二、獲取最後一個元素
1.先反轉再獲取第一個
scala> "Hello".reverse.take(1)
res11: String = o
2.takeRight()
scala> "hello".takeRight(1)
res14: String = o
3.字符串截取
scala> "hello".substring("hello".length-1)
res16: String = o
