scala学习

入门

/**
  * Object: 关键字。声明一个单例对象（伴生对象）
  *
  */
object HelloWorld {
  /**
    * def 方法名称(参数名称: 参数类型): 返回值类型={方法体}
    * @param args
    */
  def main(args: Array[String]): Unit = {
    println("Hello World")
    System.out.println("Hello Scala")
  }
}

class Student(name: String, id: Int) {
  def printInfo(): Unit = {
    println(name + "," + id + "," + Student.school)
  }

}

// 引入伴生对象
object Student {
  val school: String = "beida"

  def main(args: Array[String]): Unit = {
    val zhangsan = new Student("zhangsan", 11)
    val lisi = new Student("lisi", 22)
    zhangsan.printInfo()
    lisi.printInfo()
  }
}

•  小练习
  • 　　九层妖塔

    def main(args: Array[String]): Unit = {
        for (i <- 1 to 9; starts = 2 * i - 1; spaces = 9 - i) {
          println(" " * spaces + "*" * starts)
        }
    
        println("------------------------------")
    
        for (starts <- 1 to 17 by 2; spaces = (17 - starts) / 2) {
          println(" " * spaces + "*" * starts)
        }
    
        println("=========================")
        for (i <- 1 to 9) {
          var starts = 2 * i - 1
          var spaces = 9 - i
          println(" " * spaces + "*" * starts)
    
        }
      }