在java中访问scala类字段

Question

I have defined the class A in Scala:

class A(var number: Int)

But when I try to access its member field number in java, I get an error:

A a = new A();
a.number = 4;

Results in: java: number has private access in A . If I try to access the number from scala, there is no problem.

What can I do to get around this issue?

Answer 1

Use getter

a.number();

and setter

a.number_$eq(4);

instead of the field itself a.number .

Or

a.getNumber();
a.setNumber(4);

if you annotate the field

import scala.beans.BeanProperty

class A(@BeanProperty var number: Int)

If I try to access the number from scala, there is no problem.

In Scala when you write a.number or a.number = 4 you actually call getter/setter (this is syntax sugar).

Answer 2

You can look at the generated class file when you compile A.scala , that can explain getter number() and setter method number_$eq from Dmytro's answer

// A.scala
class A(var number: Int)

> scalac A.scala

> javap -p A.class

// output of above step

public class A {
  private int number;
  public int number();
  public void number_$eq(int);
  public A(int);
}