定义类
class MyObject private constructor(name: String, age: Int) {
private var name: String
private var age: Int = 0 init {
this.name = name
this.age = age
println("init in MyObject called")
} constructor() : this("Null", 111) {
println("constructor() in MyObject called")
} fun setName(name: String) {
this.name = name
} fun getName(): String {
return name
} fun setAge(age: Int) {
this.age = age
} fun getAge(): Int {
return age
}
}
该类中,主构造器是constructor(name: String, age: Int),次构造器是constructor()
主构造器中不能包含代码,初始化代码可以写在init { }中,次构造器可以有多个
创建类的实例,例如
val frame = JFrame("窗口")
继承
import javax.swing.JFrame class MainFrame(title: String) : JFrame(title) {
init {
setSize(300, 200)
setLocationRelativeTo(null)
defaultCloseOperation = EXIT_ON_CLOSE
} constructor() : this("未标题")
} fun main(args: Array<String>) {
MainFrame("主窗口").isVisible = true
val mainFrame = MainFrame()
mainFrame.setSize(400, 300)
mainFrame.isVisible = true
}
MainFrame继承JFrame,主构造器constructor(String),调用了基类构造JFrame(String)
参考链接:Kotlin 继承 | 菜鸟教程