1
2
3
4
5
6
7
8
9
10
11
| scala> "Application %s".format("Hello world")
val res118: String = Application Hello world
scala> "age %d".format(5)
val res119: String = age 5
scala> "char %c".format('a')
val res120: String = char a
scala> "name %s, age %d".format("Marry", 20)
val res122: String = name Marry, age 20
|
Class and Object
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
| class Point (val xc:Int, val yc: Int){
var x: Int = xc
var y: Int = yc
def move(dx:Int, dy:Int): Unit = {
x += dx
y += dy
println("new x: "+x)
println("new y: "+y)
}
}
class Location(override val xc:Int, override val yc:Int, val zc:Int)
extends Point(xc, yc){
var z:Int = zc
def move(dx:Int, dy:Int, dz:Int): Unit = {
x += dx
y += dy
z += dz
println("new x: "+x)
println("new y: "+y)
println("new z: "+z)
}
}
object Point{
def main(args: Array[String]): Unit = {
val p = new Point(10,10)
p.move(2,3)
// new x: 12
// new y: 13
val l = new Location(10, 10, 10)
l.move(3,4,5)
// new x: 13
// new y: 14
// new z: 15
}
}
|
Trait
like interface class in Java:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
| trait Animal {
def love():Unit
}
class Dog extends Animal{
def love():Unit = println("dog love meat")
}
object Animal{
def main(args: Array[String]): Unit = {
var dog = new Dog
dog.love
//dog love meat
}
}
|
Pattern Match
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
| object Animal{
def main(args: Array[String]): Unit = {
println(match1(1))
// one
println(match1(2))
// two
println(match1(10))
// many
}
def match1(x:Int):String = x match{
case 1 => "one"
case 2 => "two"
case _ => "many"
}
}
|
Case Class
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
| case class Person(name:String, age:Int)
object Person{
def main(args: Array[String]): Unit = {
val marry = new Person("Marry", 20)
val charles = new Person("Charles", 18)
val tomas = new Person("Tomas", 33)
for (person <- List(marry, charles, tomas)) {
person match {
case Person("Marry", 20) => println("Marry is 20")
case Person("Charles", 18) => println("Charles is 18")
case Person(name, age) => println("name: "+name+", age: "+age)
}
}
// Marry is 20
// Charles is 18
// name: Tomas, age: 33
}
}
|
Regular expression
1
2
3
4
5
6
7
8
9
10
11
12
13
14
| scala> val p = "h[a-z]+".r
val p: scala.util.matching.Regex = h[a-z]+
scala> p.findFirstIn("hello, how are you")
val res91: Option[String] = Some(hello)
scala> val res = p.findAllIn("hello, how are you")
val res: scala.util.matching.Regex.MatchIterator = <iterator>
scala> res.next()
val res99: String = hello
scala> res.next()
val res100: String = how
|
Exception
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
| import java.io.{FileNotFoundException, FileReader}
object Example3 {
def main(args: Array[String]): Unit = {
try {
val f = new FileReader("file1.txt")
// file not found
val a = 2/0
// other exception
}catch{
case ex: FileNotFoundException => println("file not found")
case ex: Exception => println("other exception")
}
}
}
|
Extract data from an instance, when you assign an instance to and class/object, it will trigger the unapply method to extract data.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
| object Extractor {
def main(args: Array[String]): Unit = {
val obj = Extractor("Marry")
val Extractor(name) = obj
println(name)
// Marry
}
def apply(name: String) = s"hello-$name"
def unapply(str: String):Option[String] = {
var arr = str.split("-")
if (arr.nonEmpty) {
Some(arr(1))
}else{
None
}
}
}
|
File IO
1
2
3
4
5
6
7
8
9
10
11
12
13
| import scala.io.StdIn
object IO {
def main(args: Array[String]): Unit = {
val line = StdIn.readLine()
println("your input was: "+line)
// hello, how are you
// your input was: hello, how are you
Source.fromFile("test.txt").foreach(print)
}
}
|
Generic
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
| package Day05
class Generics[A] {
private var m:A = _
def set(x:A):Unit = m=x
def get():A = m
}
object Generics {
def main(args: Array[String]): Unit = {
val g = new Generics[String];
g.set("Hello")
println(g.get)
// Hello
val g1 = new Generics[Int]
g1.set(100)
println(g1.get)
// 100
}
}
|
