为什么不交换数组索引？ [英] Why are the array indexes not being swapped?

问题描述

我试图获取要交换的数组位置，它将不起作用。无论我做什么，都无法交换它们，我知道这与编写if语句的方式有关。

I am trying to get an array position to be swapped and it will not work. No matter what I do, I cannot get them to be swapped, I know it has something to do with the way I have the if statement written.

以下是主要代码：

  Comparable[] computerSizes = new Comparable[3];

   int a = computerSizes.length - 1;



   computerSizes[0] = new Desktop("i5","Desktop",4,1024,250); 
   computerSizes[1] = new Desktop("i3","Desktop",6,512,350); 
   computerSizes[2] = new Laptop(15.6,"i3","Laptop",4,0,750); 

   for (int i = 0; i < a;i++) {

     if(computerSizes[i].compareTo(computerSizes[i+1]) == 1){
          computerSizes[i] = computerSizes[i+1];
          computerSizes[i+1] = computerSizes[i];
        }//end if
     System.out.println(computerSizes[i]);
    }//end for

这是相关的compareTo方法代码：

Here is the relevant compareTo method code:

 public int compareTo(Comparable c)
{   
    Computer a = (Computer)c;


     if (this.cost == a.cost)
        return 0;
     else if (this.cost > a.cost)
        return 1;
     else
        return -1;



}

索引0为大于索引1，但为澄清起见，我将包括相对公式：

Index at 0 is greater than index at 1 but just for clarification I will include relvant formula which is:

cost = 150 + 6.50 * super.ram + 0.15 * super.hdd + 0.48 * super.vRam;

桌面（PROCESSOR，TYPE，RAM，VRAM，HDD SPACE）：这是参数的含义。

Desktop(PROCESSOR,TYPE,RAM,VRAM,HDD SPACE): this is what the parameters mean.

推荐答案

行

computerSizes[i] = computerSizes[i+1];
computerSizes[i+1] = computerSizes[i];

不执行您期望的操作。它首先将 computerSizes [i + 1] 的值分配给 computerSizes [i] 。那时，两者是平等的。然后，将 computerSizes [i] 的值分配给 computerSizes [i + 1] 。最后，两者将相等。

don't do what you expect. It first assign the value of computerSizes[i+1] to computerSizes[i]. At that moment, both are equal. Then you assign the value of computerSizes[i] to computerSizes[i+1]. At the end, both will be equal.

为了交换值，请使用时间变量：

In order to swap the values, use a temporal variable:

Comparable temp = computerSizes[i];
computerSizes[i] = computerSizes[i+1];
computerSizes[i+1] = temp;

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