Question

我试图让数组位置被交换，但它不起作用。无论我做什么，我都无法让它们被交换，我知道这与我编写if语句的方式有关。

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

以下是相关的compareTo方法代码：

 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;



}

0处的指数大于1处的指数，但只是为了澄清我将包括relvant公式：

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

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

Answer 1

行

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

不要做你期望的事。它首先将computerSizes[i+1]的值分配给computerSizes[i]。那一刻，两者是平等的。然后，您将computerSizes[i]的值分配给computerSizes[i+1]。最后，两者都是平等的。

要交换值，请使用时间变量：

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

Answer 2

使用Temp Comparable进行SWAP

  Comparable tempComparable;
  if(computerSizes[i].compareTo(computerSizes[i+1]) == 1){
          tempCoparable = computerSizes[i];
          computerSizes[i] = computerSizes[i+1];
          computerSizes[i+1] = tempComparable;
        }//end if

Answer 3

让我们考虑一个数组：new int[3]{ 1, 2, 3 };

你在做的是：

a[i] = a[i+1];
a[i+1] = a[i];

（let i = 0）：

1. {1,2,3}   
2. {2,2,3}   |a[0] i.e. 1 gets replaced by 2
3. {2,2,3}   |a[1] i.e. 2 gets replaced by 2 (though it must be replaced by 1)

所以，必须有办法保留一个临时变量。让我们考虑以下几点：

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

这将提供所需的结果。

Answer 4

正如各种答案所说，你的交换代码不起作用，因为你没有中间变量

      myarray[i] = myarray[i+1];  // both i and i+1 now refer to the same object
      myarray[i+1] = myarray[i];  // so this line has no effect

如果您的目标是对对象进行排序，则可以通过提供比较器对象Arrays.sort()来执行此操作 - 请参阅documentation。

Answer 5

交换代码不正确。它应该是

  if(computerSizes[i].compareTo(computerSizes[i+1]) == 1){
              Computer temp = computerSizes[i]
              computerSizes[i] = computerSizes[i+1];
              computerSizes[i+1] = temp ;
            }//end if

为什么数组索引没有被交换？

5 个答案: