在 Java 中使用文本文件查找数字的平均值
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Find Average of numbers using a Text File in Java
提问by Frazer Pinheiro
package txtfileaverage;
import java.io.*;
import java.util.Scanner;
/**
*
* @author Frazer
*/
public class Txtfile {
public static void main(String args[]) throws IOException
{
Scanner file = new Scanner(new File("input.txt"));
int numTimes = file.nextInt();
file.nextLine();
for(int i = 0; i < numTimes; i++);
{
int sum = 0;
int count = 0;
Scanner split = new Scanner(file.nextLine());
while(split.hasNextInt())
//for (int a = 0; a < 4 ; a++)
{
sum += split.nextInt();
count++;
}
System.out.println("the average is = " + ((double)sum / count));
}
}
}
Text File:
文本文件：
4
100 100 100 100
100 100 50 50
100 90 80 70
60 50 40 30
the above is the text file i am trying to read from, the output that is displayed is
以上是我试图读取的文本文件，显示的输出是
"the average is 100" but it either only looks at one number or 1 line, any tips on how to get it to read the other lines? i have had a look at some tutorial and after comparing the code i'm struggling to find out why it's only finding the average of 1 number or 1 line rather than the whole row, each with another statement.
“平均值是 100”，但它要么只查看一个数字，要么只查看 1 行，关于如何让它阅读其他行的任何提示？我看过一些教程，在比较了代码之后，我正在努力找出为什么它只找到 1 个数字或 1 行的平均值，而不是整行，每个都有另一个语句。
回答by Arpit Aggarwal
With Java 8 Collectors.averagingInt, it is as simple as:
使用 Java 8 Collectors.averagingInt，它很简单：
Arrays.stream(Files.lines(Paths.get(ClassLoader.getSystemResource(
"input.txt").toURI())).reduce((a, b) -> a + " " + b)
.map(e -> e.split(" ")).get()).filter(e -> e.matches("\d+"))
.map(Integer::new)
.collect(Collectors.averagingInt(Integer::intValue));
Usage:
用法：
import java.io.IOException;
import java.net.URISyntaxException;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.Arrays;
import java.util.stream.Collectors;
public class FindAverage {
public static void main(String[] args) throws IOException,
URISyntaxException {
Double average = Arrays
.stream(Files
.lines(Paths.get(ClassLoader.getSystemResource(
"input.txt").toURI()))
.reduce((a, b) -> a + " " + b).map(e -> e.split(" "))
.get()).filter(e -> e.matches("\d+"))
.map(Integer::new)
.collect(Collectors.averagingInt(Integer::intValue));
System.out.println("Average = " + average);
}
}
回答by user10780994
Here is a simple way to calculate the average from a text file. Just write an if statement within the while loop.
这是从文本文件计算平均值的简单方法。只需在 while 循环中写一个 if 语句。
回答by Meeesh
This code here should work. What I am doing here is going through the file line by line with the while loop. With each line, I am splitting the parts by your specified delimiter, space. Then, I loop through the elements, trim()it which removes excess spaces, grab the integer, and add it to sum. For each of the integers I take, I add to count. At the very end it's the same as yours.
这里的代码应该可以工作。我在这里所做的是使用 while 循环逐行浏览文件。对于每一行，我都按您指定的分隔符空格分割部分。然后，我遍历元素，trim()它删除多余的空格，获取整数，并将其添加到总和。对于我取的每个整数，我添加计数。最后它和你的一样。
import java.io.File;
import java.io.IOException;
import java.util.Scanner;
public class Test {
public static void main(String args[]) throws IOException {
Scanner file = new Scanner(new File("input.txt"));
String line = null;
int sum = 0;
int count = 0;
while ((line = file.nextLine()) != null) {
String[] vals = line.split(" ");
for(int i = 0; i < vals.length; i++) {
sum += Integer.valueOf(vals[i].trim());
count++;
}
}
System.out.println("the average is = " + ((double) sum / count));
}
}
