82 lines
1.3 KiB
Markdown
82 lines
1.3 KiB
Markdown
# 继承和特质
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## 一、继承
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### 1.1 extends & override
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父类Person：
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```scala
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class Person {
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var name = ""
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// 1.不加任何修饰词,默认为public,能被子类和外部访问
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var age = 0
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// 2.使用protected修饰的变量能子类访问，但是不能被外部访问
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protected var birthday = ""
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// 3.使用private修饰的变量不能被子类和外部访问
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private var sex = ""
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def setSex(sex: String): Unit = {
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this.sex = sex
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}
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// 4.重写父类的方法建议使用override关键字修饰
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override def toString: String = name + ":" + age + ":" + birthday + ":" + sex
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}
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```
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使用`extends`关键字实现继承：
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```scala
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// 1.使用extends关键字实现继承
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class Employee extends Person {
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override def toString: String = "Employee~" + super.toString
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// 2.使用public或protected关键字修饰的变量能被子类访问
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def setBirthday(date: String): Unit = {
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birthday = date
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}
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}
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```
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测试继承：
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```scala
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object ScalaApp extends App {
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val employee = new Employee
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employee.name = "heibaiying"
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employee.age = 20
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employee.setBirthday("2019-03-05")
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employee.setSex("男")
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println(employee)
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}
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// 输出： Employee~heibaiying:20:2019-03-05:男
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```
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### 1.2 调用父类构造器
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### 1.3 构造顺序和提前定义
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二、抽象类
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二、特质 |