在Dart中通过引用或指针或值传递 [英] Pass by reference or pointer or value in Dart

问题描述

我正在尝试编写一些代码，以便可以通过其他类的功能将变量加起来作为对某些作品的测试.我不想写return，extends，global变量，但仍然可以添加值.有任何想法吗?还是不可能?

I am trying to write some codes that a variable can be added up by other class's function as testing for some works. I do not want to write return, extends, global variable but still can add the value. Any Ideas? Or is it impossible?

void main() {
  bbb B = new bbb();
  B.bOut();
  
}
class bbb{
  int b = 1;
  void bOut(){
    aaa A = aaa(this.b);
    A.aAdd();
    print(b);
  }
}
class aaa{
  int variableA;
  aaa(this.variableA);
  void aAdd (){
    variableA++;
  }
}

输出为1

推荐答案

欢迎来到SO Wesley！

Welcome to SO Wesley!

在Dart中，就像在许多其他面向对象的编程语言中一样，对象始终是按值传递的.但是您仍然可以按值传递指向对象和数组的指针.感谢@jamesdlin在评论中指出这一点.有关此主题的更多信息，请参见:是Java传递参考或值传递?

In Dart, as in many other object oriented programming languages, objects are always pass-by-value. But you can still pass pointers to objects and arrays by value. Thanks to @jamesdlin for pointing that out in the comments. For an more indepth look on this subject: Is Java pass-by-reference or pass-by-value?

除了传递 this.b 之外，您还可以简单地传递对对象的引用: bbb 并访问变量 b .我准备了一个简单的示例:

Instead of passing this.b you could simply pass a reference to the object: bbb and access the variable b. I've prepared a simple example:

输出:

0
1

代码:

class Wrapper {
  int i;
}

test() {
  Wrapper wrapper = Wrapper();

  wrapper.i = 0;
  print(wrapper.i);

  increase(wrapper);
  print(wrapper.i);
}

increase(Wrapper wrapper) {
  wrapper.i++;
}

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