在Java的引用传递？ [英] Pass by reference in java?

问题描述

我试图建立Android GSMS痘痘GAM。我哈瓦很多单位和所有的人都目的地。要计算我使用了一个名为的Caldes功能目标。此功能的的Caldes 是我的计算单位的速度。所以，我要送一些变量到我所编辑和再次使用他们。为此，我必须参照发送这些变量。下面是一个简单的C ++如何做到这一点在Java中？

 无效掉期（SO​​METYPE＆安培; ARG1，SOMETYPE＆安培; ARG2）{
    SOMETYPE TEMP = ARG1;
    ARG1 = ARG2;
    ARG2 =温度;
}
...
SOMETYPE VAR1 = ...; //值A
SOMETYPE VAR2 = ...; //值B
掉期（VAR1，VAR2）; //交换它们的值！
 

解决方案

Java没有通通过引用的。你有两个选择：

1. 传递数据数组：

    无效掉期（SO​​METYPE []参数）{
       SOMETYPE TEMP = ARGS [0];
       ARGS [0] = ARGS [1];
       ARGS [1] =温度;
   }
    

   ...但使用它是在调用code一痛：

     SOMETYPE一​​个= ...;
   SOMETYPE B = ...;
   SOMETYPE [] ARGS =新SOMETYPE [] {A，B};
   掉期（参数）;
   一个= ARGS [0];
   B = ARGS [1];
    




2. 创建具有公共 SOMETYPE 成员一个对象，并传递对象引用。

    无效掉期（SomeTypeContainer C）{
       SOMETYPE TEMP = C.A;
       C.A = C.B;
       C.B =温度;
   }
    

   这是非常相似，＃1，但可能更方便与调用code的工作。

     SomeTypeContainer C =新SomeTypeContainer（/ * ...的东西，创造a和b ... * /）;
   //使用C.A和C.B直接
   掉期（C）;
   //使用C.A和C.B直接，他们现在换
    

I'm trying to build a litle gam for android GSMs. I hava lots of units and all of them have destinations. To calculate destination I'm using a function called CalDes. This function CalDes is calculating my unit's speed. So I'm sending some variables into which I have to edit and use em again. For this I have to send these variables with reference. Here is a simple for C++ How to do that in java?

void swap(SomeType& arg1, Sometype& arg2) {
    SomeType temp = arg1;
    arg1 = arg2;
    arg2 = temp;
}
...
SomeType var1 = ...; // value "A"
SomeType var2 = ...; // value "B"
swap(var1, var2); // swaps their values!

解决方案

Java doesn't have pass-by-reference at all. You have a couple of options:

1. Pass the data in an array:

   void swap(SomeType[] args) {
       SomeType temp = args[0];
       args[0] = args[1];
       args[1] = temp;
   }
   

   ...but using it is a pain in the calling code:

   SomeType a = ...;
   SomeType b = ...;
   SomeType[] args = new SomeType[] { a, b };
   swap(args);
   a = args[0];
   b = args[1];
   

2. Create an object that has public SomeType members, and pass in the object reference.

   void swap(SomeTypeContainer c) {
       SomeType temp = c.a;
       c.a = c.b;
       c.b = temp;
   }
   

   Which is very similar to #1, but probably more convenient to work with from calling code.

   SomeTypeContainer c = new SomeTypeContainer(/* ... something that creates a and b ... */);
   // Use c.a and c.b directly
   swap(c);
   // Use c.a and c.b directly, they're now swapped
   

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