Scala高级语法

    implicit分类：
    （1）隐式参数
    （2）隐式转换类型
    （3）隐式类
    特点：让代码变得更加灵活

object ImplicitTest {
  //此参数
  def sleep(how:String):Unit = {println(how)}

  //此参数如果被implicit修饰的话，调用可以不写参数 直接sleep2
  def sleep2(implicit how:String = "香啊") = {println(how)}

  def main(args: Array[String]): Unit = {
    sleep("很香")

    sleep2

    implicit val how = "头疼"
    sleep2
  }
}

//隐式转换类型
object ImplicitTest1 {
  //类型转换
  implicit def double2Int(d:Double) = {d.toInt}

  def main(args: Array[String]): Unit = {
    val a:Int = 18.8
    println(a)
  }
}

object KelihuaImplicit {
  //柯理化
  def sum(a:Int)(implicit b:Int) = {a + b}

  def main(args: Array[String]): Unit = {
    //定义隐式值
    implicit val b = 9
    println(sum(1))
  }
}

import java.io.File

//扫描文件的数据条数
object FileMain {

  //定义隐式转换
  implicit def file2RichFile(file:File) = new RichFile(file)

  def main(args: Array[String]): Unit = {
    //1.加载文件
    val file = new File("e:/weblog.log")

    //2.打印条数
    println(file.count())
  }
}

import java.io.{BufferedReader, File, FileReader}

class RichFile(file:File) {
  def count():Int = {
    //读取数据
    val fileReader = new FileReader(file)
    val bufferedReader = new BufferedReader(fileReader)

    //计数器
    var sum = 0
    try {
      while (bufferedReader.readLine() != null){
        sum += 1
      }
    } catch {
      case _:Exception => sum
    } finally {
      bufferedReader.close()
      fileReader.close()
    }

    sum
  }
}

import scala.io.Source

object ReadImplicit {
  //定义隐式类
  implicit class FileRead(file:File){
    //读取文件
    def read = Source.fromFile(file).mkString
  }

  def main(args: Array[String]): Unit = {
    val file = new File("e:/weblog.log")
    println(file.read)
  }
}

    type
    如何定义scala中的泛型？

//加入泛型 T代表任意类型
abstract class Anything[T](m:T)

class Intthing[Int](m:Int) extends Anything(m) {

}

class Stringthing[String](m:String) extends Anything {

}

class Person[A,B,C](val age:A,val high:B,val face:C) {

}

object ScalaTest {
  def main(args: Array[String]): Unit = {
    val p = new Person[Int,Double,Double](18,165.5,99)
    println(p.high)
  }
}

    java中Comparable
    Scala中的比较的特质：
    Ordered
    
    上界(upper Bounds)
    <T extends Person>表示T类型是Person的子类型
    <? extends Person>
    [T <: Person]此时T是Person的子类，这种形式是上界
    [_ <: Person]
    
    def pr(list:List[_<:Any]){
        list.foreach(print)
    }
    
    下界(lower Bounds)
    <T super Person>
    <? super Person>
    
    [T >: Person]
    [_ >: Person]
    
    视图界定(View Bounds)
    <%
    视图界定发生了隐式转换
    
    上下文界定
    comparator
    scala->ordering
    上下文界定发生了隐式转换

public class Person1 implements Comparable<Person1>{
    //定义属性
    private String name;
    private int age;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public Person1(String name, int age) {
        this.name = name;
        this.age = age;
    }

    @Override
    public int compareTo(Person1 o) {
        //升序
        return this.age - o.age;
    }
}

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

public class ComTest{
    public static void main(String[] args) {
        Person1 p1 = new Person1("Tom",18);
        Person1 p2 = new Person1("Mary",16);

        List<Person1> person = new ArrayList<Person1>();
        person.add(p1);
        person.add(p2);

        Collections.sort(person);
        for (Person1 p : person) {
            System.out.println("名字为：" + p.getName());
        }
    }
}

//定义一个比较的方式
class CompareInt(a:Int,b:Int){
  def compare = if(a > b) a else b
}

//定义比较类型
class CompareC[T <: Comparable[T]](o1:T,o2:T){
  def compare = if(o1.compareTo(o2) > 0) o1 else o2
}

object UpperBounds {
  def main(args: Array[String]): Unit = {
    val big = new CompareInt(1,2)
    System.out.println(big.compare)

    val comc = new CompareC(Integer.valueOf(1),Integer.valueOf(2))
    System.out.println(comc.compare)
  }
}

//视图界定
class CompareCC[T <% Comparable[T]](o1:T,o2:T){
  def big = if(o1.compareTo(o2) > 0) o1 else o2
}

object ViewBounds {
  def main(args: Array[String]): Unit = {
    //视图界定发生了隐式转换
    val comc = new CompareCC(1,2)
    println(comc.big)
  }
}

class Compp[T:Ordering](o1:T,o2:T)(implicit comt:Ordering[T]){
  def big = if(comt.compare(o1,o2) > 0) o1 else o2
}

class Personss(val name:String,val age:Int){
  override def toString: String = this.name + "," + this.age
}

//上下文界定 同样发生了隐式转换
object ContextBounds {

  //比较器定义  比较规则
  implicit val comparatorPersonss = new Ordering[Personss]{
    override def compare(x: Personss, y: Personss): Int = x.age - y.age
  }

  def main(args: Array[String]): Unit = {
    val p1 = new Personss("Tom",18)
    val p2 = new Personss("John",15)
    val comc = new Compp(p1, p2)
    println(comc.big)
  }
}