JAVA-读取.txt文件，混合使用字符串和整数，将数组存储在数组中，将整数存储在2D数组中

Question

我有一个文本文件，在一行上有学生的姓名，然后是下一行的15个等级（每个等级分隔2个空格并在行的开头有一个空格）。

例：

    John, Elton
      89  97  91  94  82  96  98  67  69  97  87  90  100  80  92
    Johnson, Kay
      96  68  71  70  90  79  69  63  88  75  61  77  100  80  88

    (More data...)

我需要读取包含学生姓名的行并将值存储在String数组中，然后读取以下成绩行，将值存储在2D Integer数组中。 在每行整数上，前10个值被视为分配等级，而后5个值是考试等级（稍后在计算学生平均值时使用）。 当我的程序尝试读取第一个学生姓名后的整数行时，由于“输入不匹配异常”而导致程序崩溃。 到目前为止，这是我的代码：

import java.io.*;
import java.util.*;

public class Grades
{   
    // Declare constants for array lengths
    private static final int ROWS = 25;
    private static final int COLS = 15;

public static void main(String[] args) throws IOException
{
    // Create new two dimensional integer array to hold students assignment & exam grades
    int[][] grades = new int[ROWS][COLS];

    // Create new string array to hold student names
    String[] students = new String[ROWS];

    // Total number of students
    int numStudents;

    // Display your name
    System.out.println( "YOUR NAME" );

    // Fill the arrays
    numStudents = fillArray( grades, students );

    // Display the data that was just read in
    display(grades, students, numStudents);

}

 // The fillArray method opens & reads student name & grade data from a text file
private static int fillArray(int[][] sGrades, String[] sNames) throws IOException
{
    // Students counter
    int students = 0;   

    // Create the file
    File studentGrades = new File("Grades.txt");

    // Check that the file exists
    if (!studentGrades.exists())
    {
        // Display error message and exit the program
        System.out.println(studentGrades + " not found. Aborting.");
        System.exit(0);
    }

    // Create scanner object to read from the file
    Scanner gradeFile = new Scanner(studentGrades);

    // Read data until the end of the file is reached or the array is full
    while (gradeFile.hasNext() && students < sNames.length)
    {
        // Begin filling the array of student names starting with the first element
        for ( int i = 0; i < ROWS; i++ )
        {
            // Store the students name into the array's current index
            sNames[i] = gradeFile.nextLine();

            // Increment the number of students
            students++;

            // Begin filling in the array of grades starting with the first element

/*************   ERROR OCCURS HERE   ********************/
            for ( int j = 0; j < COLS; j++ )

                // Store the grade into the array's current index
                sGrades[i][j] = gradeFile.nextInt();
/**************                       *******************/
        }
    }
    // Close the file
    gradeFile.close();
    // Return the total number of students
    return students;
}
    // The display method prints Each student's name, 10 assignment 
    // grades and 5 exam grades
    // to the screen, separating each student by a blank line.
total number of students
private static void display(int[][] gradeArray, String [] studentArray, int totalStudents)
{
    //
    for ( int i = 0; i < totalStudents; i++)
    {
        System.out.println();
        //
        System.out.print("STUDENT:     " + studentArray[i]);

        System.out.print("\nASSIGNMENTS: ");
        //
        for ( int j = 0; j < 10; j++)
            //
            System.out.print(gradeArray[i][j] + " ");

        //
        System.out.print("\nEXAMS:       ");

        //
        for ( int k = 10; k < COLS; k++)
            //
            System.out.print(gradeArray[i][k] + " ");
        System.out.println();
    }

'display'方法的输出应如下所示：

    YOUR NAME

    STUDENT:     John, Elton
    ASSIGNMENTS: 89 97 91 94 82 96 98 67 69 97
    EXAMS:       87 90 100 80 92

    STUDENT:     Johnson, Kay
    ASSIGNMENTS: 96 68 71 70 90 79 69 63 88 75
    EXAMS:       61 77 100 80 88   

    (More output...)

由于程序在我看到任何输出之前崩溃，我删除了以下代码行，试图读取下一个Integer以查看发生了什么。

    for ( int j = 0; j < COLS; j++ )
        sGrades[i][j] = gradeFile.nextInt();

正如我所料，文件的每一行都被读作一个字符串，并且该值存储在学生名称数组中，从而产生如下输出：

    STUDENT:     John, Elton
    ASSIGNMENTS: 0 0 0 0 0 0 0 0 0 0
    EXAMS:       0 0 0 0 0

    STUDENT:     89 97 91 94 82 96 98 67 69 97 87 90 100 80 92
    ASSIGNMENTS: 0 0 0 0 0 0 0 0 0 0
    EXAMS:       0 0 0 0 0

    STUDENT:     Johnson, Kay
    ASSIGNMENTS: 0 0 0 0 0 0 0 0 0 0
    EXAMS:       0 0 0 0 0

    STUDENT:     96 68 71 70 90 79 69 63 88 75 61 77 100 80 88
    ASSIGNMENTS: 0 0 0 0 0 0 0 0 0 0
    EXAMS:       0 0 0 0 0

    (More output...)

我的大脑很痛苦，想弄清楚我哪里出错了。 如果我猜测，我认为它与分隔每个整数的空格有关，导致每一行的等级被解释为String而不是整数。 还是有其他我可能忽略的东西？

编辑：我只能在这个程序中使用更基本的Java技术。 我不能使用数组列表，方法标题中的throws子句以外的异常处理。 文件处理仅限于使用File ＆ Scanner类。 没有BufferReader或StringReader或FileReader 。

Answer 1

使用Integer.parseInt(gradeFile.next())而不是gradeFile.nextInt()

它的工作原理如下：

/************* ERROR OCCURS HERE ********************/
for (int j = 0; j < COLS; j++) {

    // Store the grade into the array's current index
    sGrades[i][j] = Integer.parseInt(gradeFile.next());
    /**************                       *******************/
}

if (gradeFile.hasNext())
    gradeFile.nextLine();

Answer 2

使用try和catch语句对填充进行处理，如下所示：

         try{
            sNames[i] = gradeFile.nextLine();
            }catch(Exception NoSuchElementException){   
            }

并编写for循环，生成错误：

                for ( int j = 0; j < COLS; j++ ){
                try{
                    sGrades[i][j]=gradeFile.nextInt() ;
                }catch(Exception NoSuchElementException){

                }


            }
            try{
                gradeFile.nextLine();
            }catch(Exception NoSuchElementException){

            }

在你的for循环（添加整数）后，最后一个gradeFile.nextLine（）丢失了，我用try和catch语句添加它告诉我它是否有效:)

Answer 3

嗯，我编写的应用程序做的正是你想要的。

这里是：

import java.io.BufferedReader;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.io.StringReader;
import java.util.logging.Level;
import java.util.logging.Logger;

public class Main {

    //Aka rows
    private static final int NO_STUDENTS = 25;
    //Grades per student. Aka columns.
    private static final int NO_GRADES = 15;

    //Names of all the students
    private final String[] STUDENTS = new String[NO_STUDENTS];

    //The students grades
    private final int[][] GRADES = new int[NO_STUDENTS][NO_GRADES];

    /**
     * Runs the application
     */
    public Main() {
        try {
            //Writes to the arrays from the text file
            parseReults("Results.txt");
            //Prints the results in the format
            printResults();
        } catch (IOException ex) {
            Logger.getLogger(Main.class.getName()).log(Level.SEVERE, null, ex);
        }

    }

    /**
     * Parses the students names and grades from a text file and writes them to
     * the arrays.
     *
     * @param resultsFile
     */
    private void parseReults(String resultsFile) throws IOException {
        BufferedReader reader = new BufferedReader(
                new StringReader(getTextFileContents(resultsFile)));

        int lineNo = 0;
        int studentNo = 0;
        int gradeNo = 0;
        String line;

        //Reads over every line in the file
        while ((line = reader.readLine()) != null) {
            //Is the line number odd, if so read students name else read
            //the grades
            if (lineNo % 2 == 0) {
                STUDENTS[studentNo] = line;
                studentNo++;
            } else {
                GRADES[gradeNo] = getGrades(line);
                gradeNo++;
            }

            lineNo++;
        }
    }

    /**
     * Prints the results from the arrays.
     */
    private void printResults() {
        System.out.println("YOUR NAME\n");

        for (int i = 0; i < STUDENTS.length; i++) {
            System.out.println("STUDENT: " + STUDENTS[i]);

            String assignments = "";

            for (int j = 0; j < 9; j++) {
                assignments += GRADES[i][j] + " ";
            }

            System.out.println("ASSIGNMENTS: " + assignments);

            String exams = "";

            for (int k = 9; k < 15; k++) {
                exams += GRADES[i][k] + " ";
            }

            System.out.println("EXAMS: " + exams);
            System.out.println("");
        }
    }

    public static void main(String[] args) throws IOException {
        Main m = new Main();
    }

    /**
     * Parses all the students grades from one line of text into an integer
     * array containing all the grades.
     * 
     * @param gradesLine
     * @return 
     */
    private static int[] getGrades(String gradesLine) {
        try {
            int[] grades = new int[NO_GRADES];

            StringReader reader = new StringReader(gradesLine);
            reader.read();//Get rid of the first space

            for (int i = 0; i < NO_GRADES; i++) {
                String grade = "";
                char letter;

                while ((letter = (char) reader.read()) != ' ') {
                    if (letter == '\n' || letter == (char) 65535) {
                        break;
                    }
                    grade += letter;
                }

                reader.read();//Get red of the second space
                grades[i] = Integer.parseInt(grade);
            }

            return grades;
        } catch (IOException ex) {
            //Isn't happening
        }

        return null;//Won't happen
    }

    /**
     * Reads an entire text file.
     *
     * @param fileName the name of the file
     * @return the file contents
     */
    private static String getTextFileContents(String fileName)
            throws FileNotFoundException, IOException {
        String contents = "";

        try (BufferedReader reader = new BufferedReader(
                new FileReader(new File(fileName)))) {
            String line;
            while ((line = reader.readLine()) != null) {
                contents += line + "\n";
            }
        }

        return contents;
    }
}

这是“Results.txt”文件：

John, Elton
 89  97  91 94  82  96  98  67  69  97  87  90  100  80  92
Johnson, Kay
 96  68  71  70  90  79  69  63  88  75  61  77  100  80  88
Amanda, Grey
 35  15  44  88  95  84  85  45  15  95  11  46  98  100  88

最后，这是输出：

YOUR NAME

STUDENT: John, Elton
ASSIGNMENTS: 89 97 91 4 82 96 98 67 69 
EXAMS: 97 87 90 100 80 92 

STUDENT: Johnson, Kay
ASSIGNMENTS: 96 68 71 70 90 79 69 63 88 
EXAMS: 75 61 77 100 80 88 

STUDENT: Amanda, Grey
ASSIGNMENTS: 35 15 44 88 95 84 85 45 15 
EXAMS: 95 11 46 98 100 88 

STUDENT: null
ASSIGNMENTS: 0 0 0 0 0 0 0 0 0 
EXAMS: 0 0 0 0 0 0 

STUDENT: null
ASSIGNMENTS: 0 0 0 0 0 0 0 0 0 
EXAMS: 0 0 0 0 0 0 

STUDENT: null
ASSIGNMENTS: 0 0 0 0 0 0 0 0 0 
EXAMS: 0 0 0 0 0 0 

STUDENT: null
ASSIGNMENTS: 0 0 0 0 0 0 0 0 0 
EXAMS: 0 0 0 0 0 0 

STUDENT: null
ASSIGNMENTS: 0 0 0 0 0 0 0 0 0 
EXAMS: 0 0 0 0 0 0 

STUDENT: null
ASSIGNMENTS: 0 0 0 0 0 0 0 0 0 
EXAMS: 0 0 0 0 0 0 

STUDENT: null
ASSIGNMENTS: 0 0 0 0 0 0 0 0 0 
EXAMS: 0 0 0 0 0 0 

STUDENT: null
ASSIGNMENTS: 0 0 0 0 0 0 0 0 0 
EXAMS: 0 0 0 0 0 0 

STUDENT: null
ASSIGNMENTS: 0 0 0 0 0 0 0 0 0 
EXAMS: 0 0 0 0 0 0 

STUDENT: null
ASSIGNMENTS: 0 0 0 0 0 0 0 0 0 
EXAMS: 0 0 0 0 0 0 

STUDENT: null
ASSIGNMENTS: 0 0 0 0 0 0 0 0 0 
EXAMS: 0 0 0 0 0 0 

STUDENT: null
ASSIGNMENTS: 0 0 0 0 0 0 0 0 0 
EXAMS: 0 0 0 0 0 0 

STUDENT: null
ASSIGNMENTS: 0 0 0 0 0 0 0 0 0 
EXAMS: 0 0 0 0 0 0 

STUDENT: null
ASSIGNMENTS: 0 0 0 0 0 0 0 0 0 
EXAMS: 0 0 0 0 0 0 

STUDENT: null
ASSIGNMENTS: 0 0 0 0 0 0 0 0 0 
EXAMS: 0 0 0 0 0 0 

STUDENT: null
ASSIGNMENTS: 0 0 0 0 0 0 0 0 0 
EXAMS: 0 0 0 0 0 0 

STUDENT: null
ASSIGNMENTS: 0 0 0 0 0 0 0 0 0 
EXAMS: 0 0 0 0 0 0 

STUDENT: null
ASSIGNMENTS: 0 0 0 0 0 0 0 0 0 
EXAMS: 0 0 0 0 0 0 

STUDENT: null
ASSIGNMENTS: 0 0 0 0 0 0 0 0 0 
EXAMS: 0 0 0 0 0 0 

STUDENT: null
ASSIGNMENTS: 0 0 0 0 0 0 0 0 0 
EXAMS: 0 0 0 0 0 0 

STUDENT: null
ASSIGNMENTS: 0 0 0 0 0 0 0 0 0 
EXAMS: 0 0 0 0 0 0 

STUDENT: null
ASSIGNMENTS: 0 0 0 0 0 0 0 0 0 
EXAMS: 0 0 0 0 0 0 

---

现在，它是如何工作的：

从main(String[])方法，它初始化Main的新实例。

在Main的构造函数中，调用parseResults(String fileName)方法，该方法读取文件并解析结果。 然后， printResults()方法，正如您可以通过名称猜测的那样，打印结果。

parseResults()方法：这是所有魔法发生的地方。 它首先读取整个文件，然后逐行迭代。 如果它所读取的行的行号是偶数，它将从该行获取文本并将其附加到STUDENTS数组的下一行。 如果行号为奇数，则它知道该行包含最后一个学生的成绩，因此它调用getGrades()方法，该方法将一行成绩解析成一个整数数组，其中包含文本行中的所有成绩，然后附加grade整数数组到GRADES数组的下一行。

Answer 4

尝试这样的事情

private static final int COLS = 15;

public static void computeScores() throws IOException {
    int totalStudents = 0, totalMarks = 0;
    String[] lines = new String(Files.readAllBytes(Paths.get("data.txt"))).split("[\\r\\n]+");
    String[] sNames = new String[lines.length / 2];
    int[][] grades = new int[lines.length / 2][COLS];
    if (lines.length > 0) {
        for (int i = 0; i < lines.length; i++) {
            if (i % 2 == 0) {
                sNames[totalStudents] = lines[i];
                totalStudents++;
            } else {
                String[] marks = lines[i].split("  ");
                for (int j = 0; j < marks.length; j++)
                    grades[totalMarks][j] = Integer.parseInt(marks[j].trim());
                totalMarks++;
            }
        }
    }
}

//go ahead and print out your values the usual way you've been doing it

    for (int i = 0; i < totalStudents; i++) {
        System.out.println();
        //
        System.out.print("STUDENT: " + sNames[i]);

        System.out.print("\nASSIGNMENTS: ");
        //
        for (int j = 0; j < 10; j++)
            //
            System.out.print(grades[i][j] + " ");

        //
        System.out.print("\nEXAMS: ");

        //
        for (int k = 10; k < COLS; k++)
            //
            System.out.print(grades[i][k] + " ");
        System.out.println();
    }

这应该打印得很好

Answer 5

感谢大家的投入。 我发现问题是一个不必要for循环来处理学生姓名。 我在fillArray()方法中修改了我的代码，如下所示：

private static int fillArray(int[][] sGrades, String[] sNames) throws IOException
{
    int students = 0;   // Students counter

    // Create the file
    File studentGrades = new File("Grades.txt");

    // Check that the file exists
    if (!studentGrades.exists())
    {
        // Display error message and exit the program
        System.out.println(studentGrades + " not found. Aborting.");
        System.exit(0);
    }
    // Create scanner object to read from the file
    Scanner gradeFile = new Scanner(studentGrades);

    // Read data until the end of the file is reached or array is full
    while (gradeFile.hasNext() && students < ROWS)
    {
        sNames[students] = gradeFile.nextLine();

        for ( int i = 0; i < COLS; i++ )
            sGrades[students][i] = gradeFile.nextInt();

        students++;
        gradeFile.nextLine();
    }

    // Close the file
    gradeFile.close();
    // Return the total number of students
    return students;
}

瞧！

    STUDENT:     John, Elton
    ASSIGNMENTS: 89 97 91 94 82 96 98 67 69 97 
    EXAMS:       87 90 100 80 92 

    STUDENT:     Johnson, Kay
    ASSIGNMENTS: 96 68 71 70 90 79 69 63 88 75 
    EXAMS:       61 77 100 80 88 

    STUDENT:     Liston, Ed
    ASSIGNMENTS: 78 98 98 85 96 96 64 60 81 61 
    EXAMS:       66 83 100 98 93 

    STUDENT:     Kelly, Michael
    ASSIGNMENTS: 72 64 76 76 86 100 69 87 76 79 
    EXAMS:       76 93 100 78 82 

    STUDENT:     Presley, Elvis
    ASSIGNMENTS: 92 94 100 50 82 79 72 75 78 85 
    EXAMS:       70 76 100 87 79 

    STUDENT:     Hughes, Meghan
    ASSIGNMENTS: 90 97 89 100 94 88 70 92 90 92 
    EXAMS:       91 84 100 94 71 

    STUDENT:     Madonna
    ASSIGNMENTS: 97 97 84 94 96 91 86 95 90 98 
    EXAMS:       93 91 100 98 96 

    STUDENT:     Pacino, Al
    ASSIGNMENTS: 73 71 77 70 89 100 82 0 90 77 
    EXAMS:       5 77 100 80 74 

    STUDENT:     Bush, George W.
    ASSIGNMENTS: 76 73 60 82 79 74 66 77 73 86 
    EXAMS:       70 78 100 77 90 

    STUDENT:     Burke, Maggie
    ASSIGNMENTS: 94 73 74 79 66 78 43 90 97 91 
    EXAMS:       87 79 100 67 90 

    STUDENT:     Diesel, Vin
    ASSIGNMENTS: 60 64 89 66 52 70 67 66 67 66 
    EXAMS:       55 73 100 75 45 

    STUDENT:     Spiderman
    ASSIGNMENTS: 89 75 91 99 91 80 100 98 91 78 
    EXAMS:       92 93 100 92 99 

    STUDENT:     Baggins, Bilbo
    ASSIGNMENTS: 82 81 55 89 71 74 35 68 86 96 
    EXAMS:       65 0 100 71 61 

    STUDENT:     Williams, Serena
    ASSIGNMENTS: 100 94 96 98 90 90 92 91 92 90 
    EXAMS:       88 94 100 82 92 

    STUDENT:     Baggins, Frodo
    ASSIGNMENTS: 68 78 80 73 83 74 74 67 39 81 
    EXAMS:       65 88 100 68 92 

    STUDENT:     Potter, Harry
    ASSIGNMENTS: 87 61 78 89 86 80 70 72 77 83 
    EXAMS:       65 93 100 86 67 

    STUDENT:     Cianci, Buddy
    ASSIGNMENTS: 98 70 60 91 67 81 89 64 70 77 
    EXAMS:       62 77 100 92 76 

    STUDENT:     Basilico, Anthony
    ASSIGNMENTS: 67 69 76 76 75 67 83 83 88 75 
    EXAMS:       63 63 100 82 100 

    STUDENT:     Clapton, Eric
    ASSIGNMENTS: 100 85 64 89 83 68 84 91 84 66 
    EXAMS:       81 84 100 100 95 

    STUDENT:     Lennon, John
    ASSIGNMENTS: 88 65 84 68 80 90 61 62 88 75 
    EXAMS:       74 75 100 80 76