如何比较阵列的销售额并获得最高和最低的销售额

Question

是否有人拥有能够比较阵列中的销售额或变量的代码，并能够打印出最高和最低销售额的代码。 我已经尝试了几种方法，但无法完全使其正常工作。

这是我的代码，我最关心的事情在底部：

package album;

public class Certifier {

    public static void main(String[] args) {

Album zero = new Album(0, "Dark Side of the Moon", "Pink Floyd", 1973, 50000000);

        System.out.println("The album information for ablum 0 is: " + zero.toString());

        Album one = new Album(1, "Superficial", "Heidi Montag",  2010, 658);

        System.out.println("The album information for ablum 1 is: " + one.toString());

        Album two = new Album(2, "Fearless", "Taylor Swift", 2011, 3200000);

        System.out.println("The album information for ablum 2 is: " + two.toString());

        Album three = new Album(3, "Made Up", "Sample Band", 2011, 1300000);

        System.out.println("The album information for ablum 3 is: " + three.toString());

        Album four = new Album(4, "Concerto One Night", "Andrea Bocelli", 2011, 500008);

        System.out.println("The album information for ablum 4 is: " + four.toString());

        Album[] albums = new Album[4];
            albums[0] = zero;
            albums[1] = one;
            albums[2] = two;
            albums[3] = three;
            albums[4] = four;


            ((Comparable<String>) albums[0]).compareTo(albums[1]);

        System.out.println("The highest selling album is");
        for (int i=0; i< Album[].length; i++) {
            double highestSales;
            if (i.getSales()<highestSales)
                highestSales= i;
            return highestSales;

        }

    System.out.println("The lowest selling album is");
        for (int i=0; i< Album[].length; i++) {
            double lowestSales;
            if (i.getSales()<lowestSales)
                lowestSales= i.getSales();
            return i.getName + i.getArtist;
        }
    }
}

Answer 1

Album highestSellingAlbum;
double highestSales = 0;

for (int i=0; i< albums.length; i++) 
{
  if (albums[i].getSales() > highestSales)
  {
    highestSales = albums[i].getSales();
    highestSellingAlbum = albums[i];
  }
}

highestSellingAlbum现在将包含销量最高的专辑，假设您的Album类具有正确的getSales()方法可返回销售。

Answer 2

要获得有史以来的最低lowestSales设置，您需要使用更高的值将其初始化为您所寻找的实际最低价格。 可能是Double.MAX_VALUE或您之前找到的最高销售（假设您已修复错误）。 当然，您还应该初始化highestSale，也许用0.0初始化。

mostSale的解决方法是在循环中分配highestSales = i.getSales() ；

Answer 3

这是完整且有效的版本：

package album;


public class Certifier {

    public static void main(String[] args) {

        Album zero = new Album(0, "Dark Side of the Moon", "Pink Floyd", 1973, 50000000);
        System.out.println("The album information for ablum 0 is: " + zero.toString());

        Album one = new Album(1, "Superficial", "Heidi Montag",  2010, 658);
        System.out.println("The album information for ablum 1 is: " + one.toString());

        Album two = new Album(2, "Fearless", "Taylor Swift", 2011, 3200000);
        System.out.println("The album information for ablum 2 is: " + two.toString());

        Album three = new Album(3, "Made Up", "Sample Band", 2011, 1300000);
        System.out.println("The album information for ablum 3 is: " + three.toString());

        Album four = new Album(4, "Concerto One Night", "Andrea Bocelli", 2011, 500008);
        System.out.println("The album information for ablum 4 is: " + four.toString());

        Album[] albums = new Album[5]; //we have 5 albums!
            albums[0] = zero;
            albums[1] = one;
            albums[2] = two;
            albums[3] = three;
            albums[4] = four;

        Album highestSellingAlbum = zero; //must be initialized with any of the 5
        Album lowestSellingAlbum = zero; //must be initialized with any of the 5

        for (int i=0; i< albums.length; i++) {

            if (albums[i].getSales() > highestSellingAlbum.getSales()){
                highestSellingAlbum = albums[i];
            }
            if (albums[i].getSales() < lowestSellingAlbum.getSales()){
                lowestSellingAlbum = albums[i];
            }
        }
        System.out.println("The highest selling album is " + highestSellingAlbum);
        System.out.println("The highest sales is " + highestSellingAlbum.getSales() ); 

        System.out.println("The lowest selling album is " + lowestSellingAlbum);
        System.out.println("The lowest sales is " + lowestSellingAlbum.getSales() );

    }

}

您发布的版本中存在许多错误，包括编译错误。 您应该开始在Java实验中使用像eclipse这样的IDE，因为这样的环境会在编程时向您显示错误。

对您的算法问题。 关键是，您需要初始化要比较的变量。 我想这就是您尝试的那行((Comparable<String>) albums[0]).compareTo(albums[1]); 在您的代码中？ 好吧，那条线没有意义。 另外，您正在将“专辑”数组的索引与专辑的销售额混合在一起。 好吧，看看我的解决方案并进行研究。 将来，请仅发布至少没有编译错误的代码。

Answer 4

如果可以更改相册类，则可以实现可比较接口，并且只需调用Arrays.sort(albums) ，它将使您的数组变短，您可以将数组的第一个和最后一个元素分别用作销量最低和销量最高的专辑。


代码将是这样的

public class Album implements Comparable<Album>{
     /*
      your existing code here
     */
     public int compareTo(Album compareAlbum) {
       int compareSales = ((Album) compareAlbum).getSales(); 
       return this.sales - compareSales
     }
}

如果您不能更改专辑的类别，那么格拉明的答案就可以了。