这是我为CSE 201工作的实验室.该计划应该从文件中读取有关学生及其分数的信息,并输出每个学生的姓名及其所有分数和总分,再加上平均分数.班级成绩,以及总分最高和最低的学生的姓名和总分.
这里可以看到确切的分配.
我在编译时遇到了一些麻烦,尤其是变量" students".任何帮助都会很棒.
/*
* The program will read information about students and their
* scores from a file, and output the name of each student with
* all his/her scores and the total score, plus the average score
* of the class, and the name and total score of the students with
* the highest and lowest total score.
*/
import java.util.Scanner;
public class Lab7
{
public static void main(String[] args)
{
// Input file name
Scanner in = new Scanner(System.in);
String filename = getFileName(in);
// Input number of students
int Student[students] = getStudents(FileIOHelper.getNumberOfStudents(filename));
// Input all students records and create Student array and
// integer array for total scores
int[] totalScores = new int[students.length];
for(int i = 0; i < students.length; i++){
for(int j = 1; j < 4; j++){
totalScores[i] += students[i].getScore(j);
}
}
// Compute total scores and find students with lowest and
// highest total score
int maxIndex = 0, minIndex = 0;
for(int i = 0; i < students.length; i++){
if(totalScores[i] > totalScores[maxIndex]){
maxIndex = i;
}else if(totalScores[i] < totalScores[minIndex]){
minIndex = i;
}
}
// Compute average total score
int average = 0;
for(int i = 0; i < totalScores.length; i++){
average += totalScores[i];
}
average /= students.length;
// Output results
outputResults(students, totalScores, maxIndex, minIndex, average);
}
// Given a Scanner in, this method prompts the user to enter
// a file name, inputs it, and returns it.
private static String getFileName(Scanner in)
{
System.out.print("Enter input file name: ");
return in.nextLine();
}
// Given the number of students records n to input, this
// method creates an array of Student of the appropriate size,
// reads n student records using the FileIOHelper, and stores
// them in the array, and finally returns the Student array.
private static Student[] getStudents(int n)
{
Student[] student = new Student[n];
for(int i = 0; i < student.length; i++){
student[i] = FileIOHelper.getNextStudent();
}
return student;
}
// Given an array of Student records, an array with the total scores,
// the indices in the arrays of the students with the highest and
// lowest total scores, and the average total score for the class,
// this method outputs a table of all the students appropriately
// formatted, plus the total number of students, the average score
// of the class, and the name and total score of the students with
// the highest and lowest total score.
private static void outputResults(
Student[] students, int[] totalScores,
int maxIndex, int minIndex, int average
)
{
System.out.println("\nName \t\tScore1 \tScore2 \tScore3 \tTotal");
System.out.println("--------------------------------------------------------");
for(int i = 0; i < students.length; i++){
outputStudent(students[i], totalScores[i], average);
System.out.println();
}
System.out.println("--------------------------------------------------------");
outputNumberOfStudents(students.length);
outputAverage(average);
outputMaxStudent(students[maxIndex], totalScores[maxIndex]);
outputMinStudent(students[minIndex], totalScores[minIndex]);
System.out.println("--------------------------------------------------------");
}
// Given a Student record, the total score for the student,
// and the average total score for all the students, this method
// outputs one line in the result table appropriately formatted.
private static void outputStudent(Student s, int total, int avg)
{
System.out.print(s.getName() + "\t");
for(int i = 1; i < 4; i++){
System.out.print(s.getScore(i) + "\t");
}
System.out.print(total + "\t");
if(total < avg){
System.out.print("-");
}else if(total > avg){
System.out.print("+");
}else{
System.out.print("=");
}
}
// Given the number of students, this method outputs a message
// stating what the total number of students in the class is.
private static void outputNumberOfStudents(int n)
{
System.out.println("The total number of students in this class is: \t" + n);
}
// Given the average total score of all students, this method
// outputs a message stating what the average total score of
// the class is.
private static void outputAverage(int average)
{
System.out.println("The average total score of the class is: \t" + average);
}
// Given the Student with highest total score and the student's
// total score, this method outputs a message stating the name
// of the student and the highest score.
private static void outputMaxStudent(
Student student,
int score
)
{
System.out.println(student.getName() + " got the maximum total score of: \t" + score);
}
// Given the Student with lowest total score and the student's
// total score, this method outputs a message stating the name
// of the student and the lowest score.
private static void outputMinStudent(
Student student,
int score
)
{
System.out.println(student.getName() + " got the minimum total score of: \t" + score);
}
}
首先:实际关注编译器错误总是有用的.Java的compier错误在大多数情况下非常清晰和有用,并且一旦你学会理解它们就会告诉你到底出了什么问题.一般来说,如果您包含错误的实际文本而不是说"我无法将其转换为编译器",那么SO上的人员可以更轻松地帮助您
这是第一个明显错误的路线:
int Student[students] = getStudents(FileIOHelper.getNumberOfStudents(filename));
Java中的变量声明包含(略微简化):
在上面的行中,你从type开始int,但下一部分Student[students]没有意义 - 它看起来像一个数组实例,当然不是一个名字.你可能意味着:
Student[] students = getStudents(FileIOHelper.getNumberOfStudents(filename));
即类型是Student[](学生对象的数组),名称是"学生",并且它被赋予方法的返回值getStudents().在int任何地方都不涉及(您不必在此指定数组的大小,因为它是在getStudents()方法内创建的).