java - 简单的对象和方法

Question

程序是添加和平均并列出调用“addNumber”方法的次数。

我可以让 Amount 起作用，但别无他法

public class Main {
    public static void main(String[] args) {
        NumberStatistics stats = new NumberStatistics();
        stats.addNumber(3);
        stats.addNumber(5);
        stats.addNumber(1);
        stats.addNumber(2);
        System.out.println("Amount: " + stats.amountOfNumbers());
        System.out.println("sum: " + stats.sum());
        System.out.println("average: " + stats.average());
    }

public class NumberStatistics {
    private int amountOfNumbers;
    private int addNumber; 
    private double average; 
    private int sum; 

public NumberStatistics() {
    this.amountOfNumbers=amountOfNumbers; 
    this.average=0; 
    this.sum=0;
}

public void addNumber(int number) {
    number=addNumber; 
    addNumber++; 
    // code here
}
public int amountOfNumbers() {
    return addNumber; 
    // code , here
}
public int sum() {
    return this.addNumber++; 
}

public double average() {
    return sum() / addNumber; 
}

我的错误输出:

数量:4总数:4平均值:0.0

Answer 1

好的，让我们从构造函数开始。

public NumberStatistics() {
this.amountOfNumbers=amountOfNumbers; 
this.average=0; 
this.sum=0;}

在这里，当你创建一个对象时，你将 average 和 sum 初始化为 0 但是this.amountOfNumbers=数量；没有特别的效果。总结一下我认为你想做的是这样的:

public NumberStatistics()
{
   this.average = 0;//this keyword here is not needed but i used it since you did too
   this.sum = 0;
   this.amountOfNumbers = 0;
}

然后我们转到这里的代码块:

public void addNumber(int number) {
  number=addNumber; 
  addNumber++; 
}

好吧，这一行没有意义，因为您将参数设置为等于 addNumber 变量，这对您根本没有帮助，我认为您想在这里做的是:

public void addNumber(int number) {
   sum += number;//same as sum = sum + number; 
   amountOfNumbers++;//same as amountOfNumbers = amountOfNumbers +1;
}

然后你需要一个像这样返回平均值的方法:

public double average() {
  return  average = sum / amountOfNumbers; //i use the average variable only because you did, 
  //the most efficient way here is just to return sum / amountOfNumbers
}

最后，我认为您尝试创建的最后两个方法是:

public int amountOfNumbers() {
    return amountOfNumbers; 
}

public int sum() {
  return sum; 
}

这是我的第一篇文章，希望对您有所帮助。