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1 类
(1)
scala把主构造函数放到类的定义中，让定义字段及相应方法变得简单起来。
class People(age: Int, name: String)
scala会自动将这个类变成public，默认的就是public. 如果我们将age这个字段设为 val age: Int，则scala将其定义成为一个private final 字段，并为它创建一个public方法number() 用以取值。如果var name: String，则定义name为private字段，并同时提供public的getter和setter方法。如果不做修饰，则设定为private的getter和setter方法。
class People{
println("Hello")
}
当new People时会显示输出结果：Hello
除了主构造函数，还可以通过this()副方法构造
class People(age: Int, name: String){
private var address: String = _
def this(age: Int, name: String, add: String){
this(age,name)
address = add
}
}
(2) 单例
单例实例对象无法初始化，所以不能给它的主构造函数传递参数
object test{
def calSum(start_index:Int, end_index:Int, call_fun: Int => Int) = {
var result = 0
for (i <- start_index to end_index){
result += call_fun(i)
}
result
}
def main(args: Array[String]){
if (args.length > 0) {
for (line <- Source.fromFile(args(0)).getLines)
println(line.length + " " + line)
}
else
Console.err.println("Please enter filename")
}
}
（3）继承
两点需要注意a) 重写父类方法需要显示override关键字，b）只有主构造函数才能往基类构造函数中传递参数
class People(age: Int, name: String){
override def toString() = {
"age: "+age + " name: "+name
}
}
class Man(age: Int, name: String, sex: String) extends People(age,name){
override def toString() = {
"age: "+age + " name: "+name + " sex: "+sex
}
}
简单点
class People(age: Int, name: String){
override def toString = "age: "+age + " name: "+name
}
class Man(age: Int, name: String, sex: String) extends People(age,name){
override def toString = "age: "+age + " name: "+name + " sex: "+sex
}
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原文地址：http://www.cnblogs.com/yxzfscg/p/4907472.html
