我有一个文本文件，其中包括学生的名字和成绩。我正在尝试阅读成绩并将其放入另一个方法的2d数组中，然后我想在main方法中调用它以打印出数组。但是，如果我用自己的方法调试代码，则可以打印所有内容，但是如果在main方法中调用它，则仅打印数组的最后一行。你们能告诉我我在这里想念什么吗？
这是我的文本文件：
John 25 5 4.5 5 4 5 10 10 6 9.5 5.5
Jim 25 5 4 5 4.5 5 10 4 10 9.5 7.5
Kathy 15 1 3 2 1 1.5 8 2 4 3 4
Steve 21 5 3 2 1 4 5 6 7 8 8
Stacy 15 5 1 1 1 5 3 8 9 5 7
Faith 16 3 4 2 4 4 7 5 2 3 8
这是我的方法
public static double[][] processGrades(double[][] grade) throws IOException
{
PrintWriter writer = new PrintWriter(new FileOutputStream("Output.txt"));
Scanner readNum = null;
Scanner scan = null;
int count = 0;
int count2 = 0;
int width = 0;
String[] col = null;
String[][] tempGrade = null;
String line = null;
String line2 = null;
String[] newline = null;
int maxInLine = 0;
try
{
//Create Grades Array
scan = new Scanner(new FileInputStream("input.txt"));
scan.nextLine();
while(scan.hasNext())
{
line2 = scan.nextLine();
col = line2.split(" ");
width = col.length;
count++;
System.out.println(col.length);
}
tempGrade = new String[count][width];
grade = new double[count][width];
readNum = new Scanner(new FileInputStream("input.txt"));
readNum.nextLine();
//fill Grades array
for (int i = 0; i < grade.length && readNum.hasNextLine(); i++)
{
for (int j = 0; j < grade.length && readNum.hasNextLine(); j++)
{
tempGrade[i][j] = readNum.nextLine();
String tempNum = tempGrade[i][j].replaceAll("[^0-9.0 +$]","");
// get the lines
String[] lines = tempNum.split("\\r?\\n");
// get the max amt of nums in a single line
for (String x : lines)
{
String[] temp = x.split("\\s+");
// split on whitespace
if (temp.length > maxInLine)
{
maxInLine = temp.length;
}
}
String[][] array = new String[lines.length][maxInLine]; // declare and instantiate the array of arrays
for (int o = 0; o < lines.length; o++)
{
// split on whitespace
String[] temp = lines[o].split("\\s+");
for (int f = 1; f < maxInLine; f++)
{
array[o][f] = (temp[f]);
grade[o][f] = Double.parseDouble(array[o][f]);
}
}
}
}
readNum.close();
scan.close();
writer.close();
}
catch(FileNotFoundException e)
{
System.out.println("File Not Found");
}
return grade;
}
public static void main(String[] args) throws IOException, ParseException
{
PrintWriter writer = new PrintWriter(new FileOutputStream("Output.txt"));
String[] names = null;
double[][] grades = null;
double[][] grade = null;
double[][] min =null;
double[][] max =null;
double average =0;
grades = processGrades(grade);
for(int i=0; i < grades.length; i++)
{
for(int j=0; j < grades[i].length; j++)
{
System.out.println(grades[i][j]);
}
}
writer.close();
如您所见，仅打印最后一组成绩，其余显示为0。 输出：
16.0
3.0
4.0
2.0
4.0
4.0
7.0
5.0
2.0
3.0
8.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
如果帖子的格式难以阅读或不正确，请原谅我。这是我第一次发帖，不确定要做什么。谢谢
答案 0 :(得分：1)
我必须对双数组的大小进行硬编码，并且它可以工作。这是我更新的解决方案。
public static void main(String[] arg) throws IOException {
double[][] grades = null;
double[][] gradelist = Grade(grades);
for(int i=0; i < gradelist.length; i++) {
for(int j=0; j < gradelist[i].length; j++) {
System.out.println(gradelist[i][j]);
}
}
}
public static double[][]Grade(double[][]grade) {
Scanner in = null;
try {
in = new Scanner(new FileInputStream("input.txt"));
in.nextLine();
int rows = 6;
int columns = 12;
grade = new double[rows][columns];
while(in.hasNextLine()) {
for (int i=0; i< grade.length; i++) {
String[] line = in.nextLine().trim().split(" ");
for (int j = 1; j < line.length; j++) {
grade[i][j] = Double.parseDouble((line[j]));
}
}
}
}
catch(Exception e) {
}
return grade;
}
答案 1 :(得分：0)
我建议您考虑采用以下方法。它与您当前的代码相去甚远，但我认为它更干净：
1）创建一个构造学生的课程
public class Student {
private String name;
private List<Double> grades; // can be a list of int depending on what you need
public Student(String name) {
this.name = name;
grades = new ArrayList<Double>();
}
public void setGrade(Double grade) {
grades.add(grade);
}
@Override
private String toString() {
//Override what is automatically printed when you call Student.toString() to print
}
}
在这里，我们创建了一个学生抽象。
2）一种不同的文件读取方法：
public static List<Student> load(String file) throws IOException {
List<Student> students = new ArrayList<Student>();
List<String> lines = Files.readAllLines(Paths.get(file));
for (String line : lines) {
if (!line.isEmpty()) {
ArrayList<String> partsOfLine = splitOnSpace(line);
Student s = new Student(partsOfLine.get(0));
/* Here, if the number of grades is consistently n, simply use
s.setGrade(partsOfLine.get(1));
.
.
s.setGrade(partsOfLine.get(n));
if not, use some sort of looping to set all grades */
students.add(s)
}
}
return students; // This arrayList can be passed to your print method
}
public static ArrayList<String> splitOnSpace(String line){
String[] splits = line.split(" ");
return new ArrayList<>(Arrays.asList(splits));
}
3）主体中的示例打印方法
public void print(List<Students> students){
for (Student s: students) {
System.out.println(s.toString());
}
}