在java中使类不可变 [英] making a class immutable in java

问题描述

要使一个类不可变，我能做的是：

To make a class immutable what I can do is:

1）使类最终

2）不提供setter

3）将所有变量标记为final

1)Make class final
2)do not provide setters
3)mark all variables as final

但是如果我的类有另一个类的其他对象那么，somone可以更改该对象的值

But if my class has another object of some other class then , somone can change value of that object

class MyClass{
 final int a;
 final OtherClass other 

 MyClass(int a ,OtherClass other){
  this.a = a;
  this.other = other;
 }

 int getA(){
   return a;
 }

 OtherClass getOther(){
   return other;
 }

 public static void main(String ags[]){
  MyClass m = new Myclass(1,new OtherClass);
  Other o = m.getOther();
  o.setSomething(xyz) ; //This is the problem ,How to prevent this?

}
}

推荐答案

A）使 OtherClass 不可变

或

B）不允许直接访问 OtherClass 对象，而只提供getter充当代理。

B) Don't allow direct access to the OtherClass object, instead providing only getters to act as a proxy.

编辑添加：您可以制作 OtherClass的深层副本并返回一个副本而不是原始副本，但这通常不是您在Java中所期望的行为类型。

Edit to add: You could make a deep copy of OtherClass and return a copy rather than the original, but that generally isn't the type of behavior you would expect in Java.

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