Java阅读文件/扫描器
问题描述：
我是一个初学者在java，我很努力让这个代码工作。我正在尝试读取CSV文件，然后使用该数据计算平均值，然后返回最高平均值和最高平均值的摘要。Java阅读文件/扫描器
输入如下：
艾丽西亚商标，89,90,100,95,75,85,94,100,90,92
鲍比·里克斯，98,79,87,79,9 ，98,7,19,98,78
这里是放出来应该是什么样子（数字是不正确的，例如只）：
艾丽西亚商标85.5乙
鲍比·里克斯90.0 A-
...
高98.2
低56.5
平均78.3333
import java.io.File;
import java.io.FileNotFoundException;
import java.util.ArrayList;
import java.util.Scanner;
public class Test
{
public static void main(String[] args)
{
Test x = new Test();
x.high();
}
public void high()
{
File file2 = new File("scores.csv");
try
{
Scanner scanner = new Scanner(file2);
while (scanner.hasNextLine())
{
String line2 = scanner.nextLine();
String[] value2 = line2.split(",");
// Converts String Array into Double Array
double[] score = new double[value2.length];
for (int i = 1; i < value2.length; i++)
{
score[i] = Double.parseDouble(value2[i]);
}
// Finds the sum and then the average, adds it to a array List
ArrayList<Double> av;
av = new ArrayList<Double>();
double sumNum = 0.0;
for (double i : score)
{
sumNum += i;
}
double aver = sumNum/10;
av.add(aver);
double max = 0, min = 100;
for (int a = 0; a < av.size(); a++)
{
double s = av.get(a);
max = Math.max(max, s);
min = Math.min(min, s);
aver += s;
}
System.out.println("High " + max + "");
System.out.println("Low " + min + "");
System.out.println("Average " + aver/av.size() + "");
}
scanner.close();
}
catch (FileNotFoundException e)
{
e.printStackTrace();
}
}
}
我觉得我有问题是与while循环，但我不是太确定了。任何帮助解决这个问题将非常感激。
答
您在阅读等级的函数中有一个错误。你应该修复它以这样的方式
// Converts String Array into Double Array
double[] score = new double[value2.length - 1];
for (int i = 1; i < value2.length; i++) {
score[i - 1] = Double.parseDouble(value2[i]);
}
据我了解，你想要的最大值，最小值和所有等级的平均的意思。那么你的代码应该是这样的：
package it.unitn.uvq.antonio.processor;
import java.io.File;
import java.io.FileNotFoundException;
import java.util.ArrayList;
import java.util.Scanner;
public class Test {
public static void main(String[] args) {
Test x = new Test();
x.high();
}
public void high() {
File file2 = new File("/home/antonio/Scrivania/scores.csv");
try {
Scanner scanner = new Scanner(file2);
ArrayList<Double> avgs = new ArrayList<>();
double max = 0, min = 100;
while (scanner.hasNextLine()) {
String line2 = scanner.nextLine();
String[] value2 = line2.split(",");
// Converts String Array into Double Array
double[] score = new double[value2.length - 1];
for (int i = 1; i < value2.length; i++) {
score[i - 1] = Double.parseDouble(value2[i]);
}
// Finds the sum and then the average, adds it to a array List
double sumNum = 0.0;
for (double i : score) {
sumNum += i;
min = Math.min(min, i);
max = Math.max(max, i);
}
double avg = sumNum/10;
avgs.add(avg);
System.out.println(avg);
}
scanner.close();
double avgsSum = .0;
for (double avg : avgs) {
avgsSum += avg;
}
System.out.println("High " + max + "");
System.out.println("Low " + min + "");
System.out.println("Average " + avgsSum/avgs.size() + "");
}
catch (FileNotFoundException e) {
e.printStackTrace();
}
}
}
答
如果你想只平均为每一位学生，然后最小和最大和那些总平均，你可以这样做：
编辑：添加一个例子说明你可以如何将字符转换为字符。注意：我不知道你是怎么知道它是一个B-或d +等
import java.io.File;
import java.io.FileNotFoundException;
import java.math.RoundingMode;
import java.text.DecimalFormat;
import java.util.ArrayList;
import java.util.Scanner;
public class Test {
public static void main(String[] args) {
Test x = new Test();
x.high();
}
public void high() {
// to format the scores
DecimalFormat df = new DecimalFormat("###.#");
df.setRoundingMode(RoundingMode.HALF_UP);
ArrayList<Double> averages = new ArrayList<Double>();
File file2 = new File("scores.csv");
try {
Scanner scanner = new Scanner(file2);
while (scanner.hasNextLine()) {
String line = scanner.nextLine();
String[] values = line.split(",");
// Converts String Array into Double Array
double[] scoresPerPerson = new double[values.length];
for (int i = 1; i < values.length; i++) {
scoresPerPerson[i] = Double.parseDouble(values[i]);
}
// Finds the sum and then the average, adds it to a array List
double sum = 0.0;
for (double i : scoresPerPerson) {
sum += i;
}
double average = sum/values.length;
averages.add(average);
System.out.println(values[0] + ": " + df.format(average) + " "
+ getCharGrade(average));
}
scanner.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
}
// Computes the average and get the max min
double max = 0;
double min = 100;
double totalAverage = 0;
for (double average : averages) {
if (average > max) {
max = average;
}
if (average < min) {
min = average;
}
totalAverage += average;
}
// Final step to get the general average
totalAverage /= averages.size();
// Print out the final general data
System.out.println();
System.out.println("High : " + df.format(max));
System.out.println("Low : " + df.format(min));
System.out.println("Average : " + df.format(totalAverage));
}
private String getCharGrade(double average) {
if (average >= 90) {
return "A";
} else if (average >= 80) {
return "B";
} else if (average >= 70) {
return "C";
} else if (average >= 60) {
return "D";
} else {
return "F";
}
}
}
输出：
Alicia Marks: 82,7 B
Bobby Ricks: 59,3 F
High : 82,7
Low : 59,3
Average : 71
你告诉我们你的需求，你告诉我们的代码，但你不要告诉我们你的代码有什么问题，这使我们很难帮助你。请告诉我们您的代码出了什么问题，它的行为不正确。 – 2013-05-05 19:47:21
为什么你'av = new ArrayList（）;'在每次迭代？把它放在'while'循环之外。 –
Maroun
2013-05-05 19:51:43
'这就是外观应该看起来像什么，但它看起来像什么？ – 2013-05-05 19:52:51