我的代码工作正常，唯一的问题是我的输出不正确，因为我找不到将数字数组设置回零的正确位置。这些程序的基础是接收包含具有相应等级的名称的数据。我的输出应该遵循这个标准：
Alice [87, 99, 96, 99, 86, 96, 77, 95, 70, 88]
Name: Alice
Length: 10
Average: 89.30
Median: 91.5
Maximum: 99
Mininum: 70
我得到第一个人的结果是正确的，但是，后面的结果是不正确的，因为它们包含了每个人正在读取的所有值。因此，当我的代码对那个人的数组执行操作时，下一个人将拥有“爱丽丝”的成绩加上他们自己的成绩。我有两个程序，第一个是读取数据并调用方法进行打印和操作的主程序。第二个是具有执行操作的所有方法的类。这是主程序：
public class Lab2 {
public static void main(String[] args) {
Scanner in = null; //initialize scanner
ArrayList<Integer> gradeList = new ArrayList<Integer>(); //initialize gradeList
//grab data from data.txt
try {
in = new Scanner(new File("data.txt"));
} catch (FileNotFoundException exception) {
System.err.println("failed to open data.txt");
System.exit(1);
}
//while loop to grab tokens from data
while (in.hasNext()) {
String studentName = in.next(); //name is the first token
while (in.hasNextInt()) { //while loop to grab all integer tokens after name
int grade = in.nextInt(); //grade is next integer token
gradeList.add(grade); //adding every grade to gradeList
}
//grab all grades in gradeList and put them in an array to work with
int[] sgrades = new int[gradeList.size()];
for (int index = 0; index < gradeList.size(); index++) {
sgrades[index] = gradeList.get(index); //grade in gradeList put into grades array
}
Grades myGrade = new Grades(studentName,sgrades);
testGrades(myGrade);
sgrades = null;
}
}
public static void testGrades(Grades grades) {
System.out.println(grades.toString());
System.out.printf("\tName: %s\n", grades.getName());
System.out.printf("\tLength: %d\n", grades.length());
System.out.printf("\tAverage: %.2f\n", grades.average());
System.out.printf("\tMedian: %.1f\n", grades.median());
System.out.printf("\tMaximum: %d\n", grades.maximum());
System.out.printf("\tMininum: %d\n", grades.minimum());
grades = null;
}
}
我尝试通过将其设置为空来添加位置以擦除下一个人的数组值。我没有运气。
这是包含方法的下一个程序。
public class Grades {
private String studentName; // name of course this GradeBook represents
private int[] grades; // array of student grades
/**
* @param studentName The name of the student.
* @param grades The grades for the student.
*/
public Grades(String name, int[] sgrades) {
studentName = name; // initialize courseName
grades = sgrades; // store grades
} // end two-argument GradeBook constructor
/**
* Method to convert array to a string and print.
*
* @return The name of the student with array of grades.
*/
public String toString() {
return (String) studentName + " " + Arrays.toString(grades);
}
/**
* One-argument constructor initializes studentName.
* The grades array is null.
*
* @param name The name of the student.
*/
public Grades(String name) {
studentName = name; // initialize courseName
} // end one-argument Grades constructor
/**
* Method to set the student name.
*
* @return The name of the student.
*/
public String getName() {
return studentName;
} // end method getCourseName
/**
* Method to set the length of the amount of grades.
*
* @return Number of grades for student.
*/
public int length() {
return grades.length;
}
/**
* Determine average grade for grades.
*
* @return the average of the grades.
*/
public double average() {
double total = 0; // initialize total
double average = 0.0;
// sum grades for one student, while loop
int index = 0;
while (index < grades.length) {
int grade = grades[index]; // get grade at index
total += grade;
index++; // need to increment
}
average = total / grades.length;
// return average of grades
return (double) average;
} // end method getAverage
/**
* Determine median grade for grades.
*
* @return the median of the grades.
*/
public double median() {
Arrays.sort(grades); //sort grades array
double median = 0.0;
if (grades.length%2 == 0) //checks to see if amount of grades is even/odd
//this is median if list of grades is even
median = ((double)grades[grades.length/2-1] + (double)grades[grades.length/2])/2;
else
//this is median if list of grades is odd
median = (double) grades[grades.length/2];
return (double) median;
}
/**
* Find minimum grade.
*
* @return the minimum grade.
*/
public int minimum() {
int lowGrade = grades[0]; // assume grades[0] is smallest
// loop through grades array, for loop
for (int index = 0; index < grades.length; index++) {
int grade = grades[index]; // get grade at index
// if grade lower than lowGrade, assign it to lowGrade
if (grade < lowGrade)
lowGrade = grade; // new lowest grade
} // end for
return lowGrade; // return lowest grade
} // end method getMinimum
/**
* Find maximum grade.
*
* @return the maximum grade.
*/
public int maximum() {
int highGrade = grades[0]; // assume grades[0] is largest
// loop through grades array, for-each loop
for (int grade : grades) {
// if grade greater than highGrade, assign it to highGrade
if (grade > highGrade)
highGrade = grade; // new highest grade
} // end for
return highGrade; // return highest grade
} // end method getMaximum
}
我的主要问题是，如何为我读到的每个新学生“刷新”数组？