在Eclipse中从Java访问Scala实例变量 [英] Accessing Scala instance variables from Java in Eclipse

问题描述

我怀疑我必须遗漏一些非常基本的东西，但我似乎无法从Java代码访问Scala字段：

 包装测试; 
 
 class TestScala（myNumber：Int）{
 val myNum：Int = myNumber; 
} 
 
 
包测试; 
 
 import test.TestScala; 
 
 public class TestJava {
 public static void main（String [] args）{
 TestScala t = new TestScala（2）; 
 
 int x = t.myNum; 
 
 System.out.println（x）; 
} 
} 
  

收益率：

线程中的异常mainjava.lang.Error：未解决的编译问题：
字段TestScala.myNum不可见

Assembla票涉及到这个问题，但是我的小颅骨无法解析一个有用的解决方案：

http://scala-ide.assembla.com/spaces/ scala-ide / ticket / 1238-objects-not-visible-to-java-in-mixed-java-scala-eclipse-project

谢谢

解决方案

Val域通过名称相同的方法访问。

-Xprint：typer将显示：

  class TestScala使用ScalaObject扩展java.lang.Object {
< paramaccessor> private [this] val myNumber：Int = _; 
 def this（myNumber：Int）：$ iw。$ iw.TestScala = {
 TestScala.super.this（）; 
（）
}; 
 private [this] val myNum：Int = TestScala.this.myNumber; 
< stable> <存取> def myNum：Int = TestScala.this.myNum 
} 
  

所以在Java int x = t.myNum（）; 工作。

I suspect I must be missing something very elementary but I can't seem to access Scala fields from Java code:

package test;

class TestScala (myNumber : Int){
    val myNum : Int = myNumber;
}


package test;

import test.TestScala;

public class TestJava {
    public static void main(String[] args) {
        TestScala t = new TestScala(2);

        int x = t.myNum;

        System.out.println(x);      
    }
}

Yields:

Exception in thread "main" java.lang.Error: Unresolved compilation problem: The field TestScala.myNum is not visible

This Assembla ticket touches on the subject but my tiny cranium cannot parse a useful solution:

http://scala-ide.assembla.com/spaces/scala-ide/tickets/1238-objects-not-visible-to-java-in-mixed-java-scala-eclipse-project

Thanks

解决方案

Val fields are accessed through methods with same name.

scalac -Xprint:typer will show you that:

class TestScala extends java.lang.Object with ScalaObject {
  <paramaccessor> private[this] val myNumber: Int = _;
  def this(myNumber: Int): $iw.$iw.TestScala = {
    TestScala.super.this();
    ()
  };
  private[this] val myNum: Int = TestScala.this.myNumber;
  <stable> <accessor> def myNum: Int = TestScala.this.myNum
}

So in Java int x = t.myNum(); works.

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