快学Scala 第二十课 （trait的构造顺序）

trait的构造顺序：

首先调用超类构造器特质构造器在超类构造器之后，类构造器之前执行特质从左向右被构造每个特质当中，父特质先被构造如果多个特质共有一个父特质，而那个父特质已经被构造，则不会被再次构造所有特质构造完毕，子类被构造

 

class Account { println("Account constructor") } trait Logged { println("Logged constructor") def log(msg: String){ println("Logged")} } trait LongLogger extends Logged{ println("LongLogger constructor") override def log(msg: String){ println("LongLogger") super.log(msg) } } trait ShortLogger extends Logged{ println("ShortLogger constructor") override def log(msg: String){ println("ShortLogger") super.log(msg) } } trait ConsoleLogger extends Logged { println("ConsoleLogger constructor") override def log(msg: String){ println("ConsoleLogger") super.log(msg) } } trait DetailedLogger{ println("DetailedLogger constructor") def log2(msg: String){ println("DetailedLogger") } } class SavingsAccount extends Account with LongLogger with ShortLogger with ConsoleLogger { println("SavingsAccount constructor") log("funds") } new SavingsAccount() with DetailedLogger

 

运行结果：

Account constructorLogged constructorLongLogger constructorShortLogger constructorConsoleLogger constructorSavingsAccount constructorConsoleLoggerShortLoggerLongLoggerLoggedDetailedLogger constructor

 

转载于:https://www.cnblogs.com/AK47Sonic/p/7429901.html