尝试编写一个方法来从数组中找到最大的对象

huangapple
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英文:

Trying to write a method to find the largest object from an array

问题

添加一个方法

  1. public static Measurable max(Measurable[] objects)

到Data类中，该方法返回具有最大度量值的对象。

这是我所拥有的代码。

  1. public interface Measurable {
  2.     double getMeasure();
  3. }
  5. public class MeasurableTester {
  6.     public static void main(String[] args) {
  7.         Measurable[] accounts = new Measurable[3];
  8.         accounts[0] = new BankAccount(0);
  9.         accounts[1] = new BankAccount(10000);
  10.         accounts[2] = new BankAccount(2000);
  12.         double averageBalance = Data.average(accounts);
  13.         System.out.println("平均余额：" + averageBalance);
  14.         System.out.println("预期结果：4000");
  16.         Measurable[] countries = new Measurable[3];
  17.         countries[0] = new Country("Uruguay", 176220);
  18.         countries[1] = new Country("Thailand", 513120);
  19.         countries[2] = new Country("Belgium", 30510);
  21.         double averageArea = Data.average(countries);
  22.         System.out.println("平均面积：" + averageArea);
  23.         System.out.println("预期结果：239950");
  24.     }
  25. }
  1. public class Data {
  2.     Object tempObj = new Object();
  4.     public static double average(Measurable[] objects){
  5.         double sum = 0;
  6.         for (Measurable obj : objects){
  7.             sum = sum + obj.getMeasure();
  8.         }
  9.         if (objects.length > 0) {
  10.             return sum / objects.length;
  11.         }else{
  12.             return 0;
  13.         }
  14.     }
  16.     // 我在这里尝试编写一个方法
  18.     public static Measurable max(Measurable[] objects){
  19.         double max = 0;
  20.         for (Measurable obj : objects){
  21.             if (obj.getMeasure() > max){
  22.                 max = obj.getMeasure();
  23.             }  
  24.         }
  25.         return max;
  26.     }
  27. }

注意：我已经将代码中的HTML实体编码（例如"和>）替换为了正常的引号和符号。如果您在代码中使用这些修饰符，可以恢复它们。

英文:

Add a method
public static Measurable max(Measurable[] objects)
to the Data class that returns the object with the largest measure.

This is what I have for code.

  1. public interface Measurable
  2. {
  3. double getMeasure();
  4. }
  6. public class MeasurableTester {
  8. public static void main(String[] args) {
  9.     Measurable[] accounts = new Measurable[3];
  10.     accounts[0] = new BankAccount(0);
  11.     accounts[1] = new BankAccount(10000);
  12.     accounts[2] = new BankAccount(2000);
  13.     
  14.     double averageBalance = Data.average(accounts);
  15.     System.out.println("Average balance: " + averageBalance);
  16.     System.out.println("Expected: 4000");
  17.     
  18.     Measurable[] countries = new Measurable[3];
  19.     countries[0] = new Country("Uruguay", 176220);
  20.     countries[1] = new Country("Thailand", 513120);
  21.     countries[2] = new Country("Belgium", 30510);
  22.     
  23.     double averageArea = Data.average(countries);
  24.     System.out.println("Average area: " + averageArea);
  25.     System.out.println("Expected: 239950");
  26. }
  28. }`

'''
and the part I am having problems with
'''

  1. public class Data {
  2.      Object tempObj = new Object();
  4. public static double average(Measurable[] objects){
  5.     double sum = 0;
  6.     for (Measurable obj : objects){
  7.         sum = sum + obj.getMeasure();
  8.     }
  9.     if (objects.length > 0) {
  10.         return sum / objects.length;
  11.     }else{
  12.         return 0;
  13.     }
  14. }

'''

//I am trying to come up with a method here

  1. public static Measurable max(Measurable[] objects){
  2.     double max = 0;
  3.     for (Measurable obj : objects){
  4.       if (obj.getMeasure() > max){
  5.           obj =  max;
  6.       }  
  7.     }
  8.    return max;
  9.   }
  10.  }

答案1

得分: 2

max方法应该如下所示：

  1. public static Measurable max(Measurable[] objects) {
  2.    Measurable max = null;
  3.    for (Measurable obj : objects) {
  4.        if (max == null || obj.getMeasure() > max.getMeasure()) {
  5.               max = obj;
  6.        }  
  7.     }
  8.    return max;
  9. }

如果你使用的是Java 8，你可以这样写：

  1. public static Measurable max(Measurable[] objects) {
  2.   return Arrays.stream(objects).max(Comparator.comparing(Measurable::getMeasure)).get();
  3. }

另外，使用以下代码片段时：

  1. for (Measurable obj : objects){

没有进行null检查会导致出现NullPointerException。

---- 编辑 ------

使用max方法：

  1. Measurable max = Data.max(countries) // 得到包含最大测量值的对象
  2. System.out.println(max.getMeasure()) // 打印最大测量值
英文:

The max method should be like:

  2. public static Measurable max(Measurable[] objects) {
  3.    Measurable max = null;
  4.    for (Measurable obj : objects) {
  5.        if (max == null || obj.getMeasure() > max.getMeasure()) {
  6.               max = obj;
  7.        }  
  8.     }
  9.        return max;
  10. }

If you're using Java 8, you could do:

  1. public static Measurable max(Measurable[] objects) {
  2.   return Arrays.stream(objects).max(Comparator.comparing(Measurable::getMeasure)).get();
  3. }

Also, using

  1. for (Measurable obj : objects){

without null check is a recipe for NullPointerException.

---- Edit ------<br>
Using the max method:

  1. Measurable max = Data.max(countries) // gives max measure containing object
  2. System.out.println(max.getMeasure()) // prints the max measure value

huangapple
  • 本文由 发表于 2020年8月30日 11:50:34
  • 转载请务必保留本文链接：https://go.coder-hub.com/63653773.html
  • arrays
  • java
  • max
  • object
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