我有一个文本文件，其中一行包含学生的姓名，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）。
例如：
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以查看发生的情况。
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姓名数组中，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，除方法标题中的throws子句之外的异常处理。文件处理仅限于使用File＆amp; Scanner个班级。否BufferReader或StringReader或FileReader。
答案 0 :(得分：0)
使用Integer.parseInt(gradeFile.next())代替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();
答案 1 :(得分：0)
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){
}
并编写生成错误的for循环：
for ( int j = 0; j < COLS; j++ ){
try{
sGrades[i][j]=gradeFile.nextInt() ;
}catch(Exception NoSuchElementException){
}
}
try{
gradeFile.nextLine();
}catch(Exception NoSuchElementException){
}
你的for循环（添加整数）之后缺少最后一个gradeFile.nextLine（），我用try和catch语句添加了它 告诉我它是否有效:)
答案 2 :(得分：0)
我已经编写了一个应用程序来完全你想要的东西。
这是：
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，它是如何运作的：
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，调用printResults()方法，正如您可以通过名称猜测的那样，打印结果。
parseResults()方法：
这就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。如果行号是奇数，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，然后它将成绩整数数组附加到GRADES数组的下一行。
答案 3 :(得分：0)
试试这样的东西
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
答案 4 :(得分：0)
感谢大家的投入。我发现问题是处理学生姓名的不必要的for循环。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