一. 对象
1. getter 和 setter, public 字段自带这两个方法，
age 拥有age, age= 两个方法
name 只有name= 方法,
address 拥有address, address= , getAddress(), setAddress(newValue: String) 方法
import scala.reflect.BeanProperty
class Counter {
var age = 0
val name = "haha"
@BeanProperty var address: String = _
}
object Test {
def main(args: Array[String]): Unit = {
val counter = new Counter()
counter.age = 21
println(counter.age)
println(counter.name)
counter.setAddress("beijing")
println(counter.getAddress)
}
}
2. 主构造器和辅助构造器
class Person(){
var name: String = _
var age: Int = _
var address: String = _
def this(name: String) = {
this()
this.name = name
}
def this(name: String, age: Int) = {
this(name)
this.age = age
}
}
object Test {
def main(args: Array[String]): Unit = {
val p0 = new Person() // 主
println("p0 name:" + p0.name + " age:" + p0.age + " address:" + p0.address)
val p1 = new Person("haha") //辅助
println("p1 name:" + p1.name + " age:" + p1.age + " address:" + p1.address)
val p2 = new Person("haha", 21) //辅助
println("p2 name:" + p1.name + " age:" + p2.age + " address:" + p2.address)
}
}
3. 嵌套类
class P1{
class P2{
def test() = {
println("i am method")
}
}
def test() = {
new P2().test
}
}
object Test {
def main(args: Array[String]): Unit = {
new P1().test
}
}
二. 对象
1. 单例对象
类的对象实例只有一个
2. 伴生对象，单例方法写在object 对应的类，实例方法写在 class 对应的类， 他们之间可以相互访问私有域
object P1{
def t1() = {
println("i am t1")
}
}
class P1{
def t2() = {
println("i am t2")
}
}
object Test {
def main(args: Array[String]): Unit = {
P1.t1
new P1().t2
}
}
3. 应用程序对象， 没有main 可以运行
object Test extends App{
println("i a println")
}
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