Scala 学习笔记之集合(3)

建立一个Java类，为了演示Java集合类型向Scala集合的转换：

import java.util.ArrayList;
import java.util.List;

public class School {

    public List<String> ls = null;

    public School() {
        ls = new ArrayList<String>();
        ls.add("abc");
        ls.add("efg");
    }

}

import collection.JavaConverters._
import com.citi.java.School

object CollectionDemo4 {
  def main(args: Array[String]): Unit = {
    //List转String,并且用，分隔
    println(List(1,2,3,4,5).mkString(", "))
    //List转ArrayBuffer
    println(List(1,2,3).toBuffer)
    //Map转List
    println(Map("a" -> 1, "b" -> 2).toList)
    //List转Map
    println(List("a" -> 1, "b" -> 2).toMap)
    println(List(("a",1), ("b", 2)).toMap)
    //Set转Map
    println(Set("a" -> 1, "b" -> 2).toMap)
    println(Set(("a",1), ("b",1)).toMap)
    //List转Set
    println(List(1,2,3).toSet)
    //Set转List
    println(Set(1,2,3).toList)
    //包括集合类型的String
    println(List(1,2,3).toString())
    //java集合类型转scala集合类型
    val s = new School()
    println(s.ls.asScala.toList)

  }
}

运行结果：

1, 2, 3, 4, 5
ArrayBuffer(1, 2, 3)
List((a,1), (b,2))
Map(a -> 1, b -> 2)
Map(a -> 1, b -> 2)
Map(a -> 1, b -> 2)
Map(a -> 1, b -> 1)
Set(1, 2, 3)
List(1, 2, 3)
List(1, 2, 3)
List(abc, efg)