[英]How to find the average of double values in an array list using a do loop?
[英]JAVA: Find the average of a double array list
尝试在控制台中输入一个双精度的数组列表,然后当用户以ctrl-z或d结束arraylist输入时,找到使用双精度输入的数字列表的平均值。
我从中得到很多错误,我不确定为什么! 感谢所有帮助,因为我是Java初学者
public static void main(String[] args) {
ArrayList<Double> numbers = new ArrayList<Double>();
Scanner in = new Scanner(System.in);
while (in.hasNextDouble())
{
Double input = in.nextDouble();
numbers.add(input);
}
in.close();
for (Double element : numbers) {
Double sum += element;
System.out.println(sum/numbers.size());
}
}
要计算最终均值:
double sum = 0;
for(double d : numbers) {
sum += d;
}
System.out.println(sum / numbers.size());
// don't miss the imports
import java.util.ArrayList;
import java.util.Scanner;
// you might have missed to add your main() method in a class
public class Average {
public static void main(String[] args) {
// This part was ok
ArrayList<Double> numbers = new ArrayList<Double>();
Scanner in = new Scanner(System.in);
while (in.hasNextDouble()) {
Double input = in.nextDouble();
numbers.add(input);
}
in.close();
// Forgot to initialize the value of sum
Double sum = 0d;
for (Double element : numbers) {
// add the element
sum += element;
// don't count the average here
}
// count it outside the loop
System.out.println(sum / numbers.size());
}
}
Double sum += element;
那不是合法的语法,您正在尝试向变量定义中添加某些内容,这是行不通的。 不过你近了。 只需在for
循环外声明变量sum
。
double sum = 0;
for (double element : numbers) {
sum += element;
}
System.out.println(sum/numbers.size());
您也可能不想每次都打印出当前平均值,因此您应该将其移动到循环之后。
我在代码中添加了Scanner
和collections classes
所需的java.util
包,主要问题是在for
循环中,请标记为answer。 谢谢 :)
import java.util.*;
public class Test {
public static void main(String[] args) {
Double sum=0.0;
ArrayList<Double> numbers = new ArrayList<Double>();
Scanner in = new Scanner(System.in);
while (in.hasNextDouble())
{
Double input = in.nextDouble();
numbers.add(input);
}
in.close();
for (Double element : numbers) {
sum += element;
}
System.out.println(sum/numbers.size());
}
}
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