object ScalaObjectDemo extends  App { 
    println("hello cc i miss you very much"); 
    def say(name:String){
        println(name)
    }
 
    /**
      * 先去調(diào)用java方法
      * @return
      */
    def say3(): Int ={
        println("這里是scala的方法了")
        var tmp=JavaDemo.say2("4");
        println(tmp);
        tmp
    }
}

2. JAVA中調(diào)用Scala的方法

public class JavaDemo {
    public static void main(String[] args) {
        ScalaObjectDemo.main(new String[]{}); 
        ScalaObjectDemo.say("cc ");
 
        //測(cè)試反復(fù)的方法調(diào)用
        int say3 = ScalaObjectDemo.say3();
        System.out.println(say3); 
    } 
 
    public static int say2(String age){
        System.out.println("這里是java的static 方法了"+age);
        return Integer.parseInt(age);
    }
}

3.Scala中的非靜態(tài)方法

class ScalaClassDemo { 
  def hi(name:String):Int={
    println(name)
    1
  }
}

4.Java中的調(diào)用

int zhaojun = new ScalaClassDemo().hi("cc");
System.out.println(zhaojun);

經(jīng)過測(cè)試全部能正常運(yùn)行。

scala中調(diào)用java方法報(bào)錯(cuò)

有一個(gè)java方法返回一個(gè)對(duì)象

public Map<String, String> getFieldTypeMap() {
    ...
}

現(xiàn)在在scala中調(diào)用該方法

val fieldTypeMap = someObject.getFieldTypeMap()
val innerSQL = fieldTypeMap.map { case (key: String, value: String) => key.replace(".", "_")}.toStream.sorted.reduce(_ + "," + _)

報(bào)錯(cuò)：

Error:(19, 35) value map is not a member of java.util.Map[String,String]

val structureSQL = fieldTypeMap.map{ case (key: String, value: String) => key.replace(".", "_")

~~需要添加：~~

@Deprecated
import scala.collection.JavaConversions._

需要添加：

import scala.collection.JavaConverters.mapAsScalaMapConverter

然后在使用時(shí)用toScala:

val fieldTypeMap = someObject.getFieldTypeMap()
val innerSQL = fieldTypeMap.toScala.map { case (key: String, value: String) => key.replace(".", "_")}.toStream.sorted.reduce(_ + "," + _)

以上為個(gè)人經(jīng)驗(yàn)，希望能給大家一個(gè)參考，也希望大家多多支持腳本之家。

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