java - 如何获得将二维数组打印到java中的两个文件的功能？

Posted 2023-02-26

【中文标题】java - 如何获得将二维数组打印到java中的两个文件的功能？

【英文标题】：How do I get the function to print out a 2D array into two files in java?

【发布时间】：2016-03-17 05:48:00

【问题描述】：

我的目标是获取一个包含名称和数字的文件，第一行将命名列，后面的行将是数据。列 0 将具有名字，而 1 将具有将组合的姓氏。第 2、3 和 4 列将包含 3 个将一起平均的数字，第 5 到 11 列也将包含将一起平均的数字。这将是测试数据：

first, last, #1, #2, #3, #4, #5, #6, #7, #8, #9, #10
Dan, Smith, 56, 58, 55, 66, 44, 78, 60.33, 52.33, 70.66, 44
Sam, Will, 77, 88, 55, 99, 77, 10, 62, 65, 59, 62

从这里开始，两个输出文件将包含相同的信息，第二个输出文件将以更整洁的方式分隔信息。我想要的输出是：

name, exam score,hw score,min score
Dan Smith, 56.33, 62.66, 56.33
Sam Will, 73.33, 62, 62

这一行将只用于第二个输出文件：

out.printf("%20s: %10.2f, %8.2f, %9.2f\r\n",name, average1, average2, smallestaverage);

我的代码如下，我尝试测试看看是否可以使用 for 循环打印出部分数据，但只能接收为两个变量设置的原始值：

import java.util.Scanner;
import java.util.ArrayList;
import java.io.File;
import java.io.PrintWriter;
public class compute_grades 
    public static void process_grades(String input_name, String csv_name, String pretty_name) 
        String[][] data = read_spreadsheet(input_name);
        String csvname = "csv_name.txt";
        String pretty = "pretty_name.txt";
        PrintWriter out = null;
        try 
            out = new PrintWriter(input_name);
         catch (Exception e) 
            System.out.printf("Error: failed to open file %s.\n", input_name);
            System.exit(0);
        
        String first = "dog";
        String last = "dat";
        for (int i = 0; i < data.length; i++) 
            first = data[i][0];
            last = data[i][1];
        
        System.out.println(first + last);
    
    public static String[][] read_spreadsheet(String filename) 
        ArrayList < String > lines = read_file(filename);
        if (lines == null) 
            return null;
        
        int rows = lines.size();
        String[][] result = new String[rows][];
        for (int i = 0; i < rows; i++) 
            String line = lines.get(i);
            String[] values = line.split(",");
            result[i] = values;
        
        return result;
    
    public static ArrayList < String > read_file(String filename) 
        File temp = new File(filename);
        Scanner input_file;
        ArrayList < String > result = new ArrayList < String > ();
        try 
            input_file = new Scanner(temp);
         catch (Exception e) 
            System.out.printf("Failed to open file %s\n", filename);
            return result;
        
        while (input_file.hasNextLine()) 
            String line = input_file.nextLine();
            result.add(line);
        
        input_file.close();
        return result;
    
    public static void main(String[] args) 
        Scanner in = new Scanner(System. in );
        System.out.printf("Please enter the name of the input file: ");
        String input_name = in .next();
        System.out.printf("Please enter the name of the output CSV file: ");
        String csv_name = in .next();
        System.out.printf("Please enter the name of the output pretty-print file: ");
        String pretty_name = in .next();
        process_grades(input_name, csv_name, pretty_name);
        System.out.printf("\n\nExiting...\n");
    

【参考方案1】：

我不明白你的两个输出文件之间的区别，但我认为你的过程方法应该是这样的：

public static void process_grades(String input_name, String csv_name, String pretty_name) 
    String[][] data = read_spreadsheet(input_name);

    PrintWriter out = null;
    try 
        out = new PrintWriter(csv_name);
     catch (Exception e) 
        System.out.printf("Error: failed to open file %s.\n", input_name);
        System.exit(0);
    
    // print header
    out.printf("name, exam score,hw score,min score\r\n");
    // go throu all the other rows
    for (int row = 1; row < data.length; row++) 
        // get Name
        String name = data[row][0] + " "+ data[row][1];
        // avg the next three cols
        double average1 = 0;
        for(int col = 2; col < 5; col++)
            average1 += Double.parseDouble(data[row][col].trim());
        average1 /= 3;
        // avg the next seven cols
        double average2 = 0;
        for(int col = 5; col < 12; col++)
            average2 += Double.parseDouble(data[row][col].trim());
        average2 /= 7;
        //get min score
        double smallestaverage = Math.min(average1,average2);
        // print the content
        out.printf("%20s: %10.2f, %8.2f, %9.2f\r\n",name, average1, average2, smallestaverage);
    
    // flush the output and close the writer
    out.flush();
    out.close();

【讨论】：

我稍微修改了一下，以便创建两个输出文件。 PrintWriter out1 = null; PrintWriter out2 = null; try out1 = new PrintWriter(csv_name); out2 = new PrintWriter(pretty_name); etc 等只是添加了第二个输出并更改了标签的初始 out.printf 语句和最后的 out.printf 以便它在两个文件上打印相同的信息