如何在Java中将文本文件中的数据读入数组，跳过某些元素
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How to read data from a text file into arrays in Java, skip certain elements
提问by user2769894
I need help with an assignment I have to do for my class. I have only just started with Java so i'm pretty new with it. I need to write a code that will scan numbers from a text file then calculate them and create some averages. I used a for loop to scan the file but I don't know how to scan it so it skips every third line. I need each column of text rather than each line. The text file contains 3 columns and 7 rows.
我需要帮助完成我必须为我的班级做的作业。我刚刚开始使用 Java，所以我对它很陌生。我需要编写一个代码来扫描文本文件中的数字，然后计算它们并创建一些平均值。我使用 for 循环来扫描文件，但我不知道如何扫描它，因此它每三行跳过一次。我需要每一列文本而不是每一行。文本文件包含 3 列和 7 行。
public static void main(String [] args){
readData("Sample.in");
}
static void readData(String fileName){
try{
int[] breakfast= new int[7];
int[] lunch=new int[7];
int[] dinner= new int[7];
File input = new File(fileName); // Creates Scanner to read line from the text file
Scanner scanLine = new Scanner(input); // Reads entire line from the file
String line= scanLine.nextLine(); // To read numbers from the Line buffer
Scanner scanNumber = new Scanner(line); // to read three numbers from the line buffer
for(int meal =0; meal<3; meal++){ // Checks whether the number is present in the line
if(scanNumber.hasNextInt()){ // read number from the line buffer and store it in the calories variable
int calories = scanNumber.nextInt();
System.out.print(calories+" ");
}
}
System.out.println("");
} catch(FileNotFoundException e){ // catches exception in case the file is missing
System.out.println(e);
}
}
Example input file:
示例输入文件：
200 1000 800
450 845 1200
800 250 400
0 1500 1800
600 500 1000
700 1400 1700
675 400 900
回答by DwB
Here is a non-code solution
这是一个非代码解决方案
- Open the file.
- Create the scanner.
- while (scanner.hasNextLine())
- use the scanner and read one line.
- split the line using String.split(); // read the api and use the version of split that matches your requirements.
- split returns an array. you care about elements 0, 1, and 2.
- Convert elements 0, 1, and 2 to an integer (read Integer in the api documentation).
- add elements 0, 1, and 2 to Lists.
- 打开文件。
- 创建扫描仪。
- 而 (scanner.hasNextLine())
- 使用扫描仪读取一行。
- 使用 String.split() 分割线；// 读取 api 并使用符合您要求的 split 版本。
- split 返回一个数组。你关心元素 0、1 和 2。
- 将元素 0、1 和 2 转换为整数（在 api 文档中阅读 Integer）。
- 将元素 0、1 和 2 添加到列表中。
Some java into:
一些java变成：
List<Integer> breakfast = new ArrayList<Integer>();
List<Integer> dinner = new ArrayList<Integer>();
List<Integer> lunch = new ArrayList<Integer>();
// add an element to breakfast:
breakfast.add(blammy);
// Iterate through dinner:
int dinnerTotal = 0
for (Integer current : dinner)
{
dinnerTotal += current.intValue();
}
