import java.awt._ // 引入包内所有成员
def handler(evt: event.ActionEvent) {
// java.awt.event.ActionEvent
... // 因为引入了java.awt,所以可以省去前面的部分
}
import java.awt.{
Color, Font}
// 重命名成员
import java.util.{
HashMap => JavaHashMap}
// 隐藏成员
import java.util.{
HashMap => _, _} // 引入了util包的所有成员,但是HashMap被隐藏了
Symbolic literal
Symbol type is generally used for quick comparison, such as Map type: Map<Symbol, Data>, according to a Symbol object, you can quickly query the corresponding Data, while the query efficiency of Map<String, Data> is much lower.
Reprinted: Understanding Symbol in scala
for (a <- 1 to 10; b <- 1 until 10
if a * b > 50
) {
println(a + " , " + b)
}
//IndexedSeq[Int]
var retVal = for {
a <- 1 to 10 if a != 3} yield a
In Scala, you can use the val statement to define functions, and the def statement to define methods.
def m(x: Int) = x + 2
val f = (x: Int) => x + 2
Higher order function, template
// 函数 f 和 值 v 作为参数,而函数 f 又调用了参数 v
def apply(f: Int => String, v: Int): String = f(v)
def layout[A](x: A): String = "[" + x.toString() + "]"
Partial function
val logWithDateBound = log(date, _ : String)