我的readData方法有很多代码，我必须单独键入每个对象以向其中添加信息。无论我尝试多少次，我都无法弄清楚如何将arrayList放到这里。
有人可以告诉我如何制作一个arraylist，我将能够使用循环添加所有这些信息。感谢
编辑readData方法是我在为正在添加信息的对象创建循环时遇到的问题。有没有办法可以循环它，所以我不需要有太多的信息并保留这部分
person1.setStudentID(studentID); inputFile.nextLine(); fullName = inputFile.nextLine(); person1.setFullName(fullName); testScore = inputFile.nextDouble(); person1.setTestScore(testScore); person1.setGrade(testScore); averageScore = averageScore + testScore; studentID = inputFile.nextInt(); person2.setStudentID(studentID); inputFile.nextLine(); fullName = inputFile.nextLine(); person2.setFullName(fullName); testScore = inputFile.nextDouble(); person2.setTestScore(testScore); person2.setGrade(testScore); averageScore = averageScore + testScore;
public class GradeDriver {
public static void main(String[] args) {
final String STUDENT_INFO = "HW1_Students.txt";
List<GradeInfo> list = new ArrayList<GradeInfo>();
Scanner inputFile = null;
GradeInfo person1 = new GradeInfo();
GradeInfo person2 = new GradeInfo();
GradeInfo person3 = new GradeInfo();
GradeInfo person4 = new GradeInfo();
GradeInfo person5 = new GradeInfo();
GradeInfo person6 = new GradeInfo();
GradeInfo person7 = new GradeInfo();
GradeInfo person8 = new GradeInfo();
GradeInfo person9 = new GradeInfo();
GradeInfo person10 = new GradeInfo();
GradeInfo calculatedValues = new GradeInfo();
list.add(person1);
list.add(person2);
list.add(person3);
list.add(person4);
list.add(person5);
list.add(person6);
list.add(person7);
list.add(person8);
list.add(person9);
list.add(person10);
try {
inputFile = new Scanner(new File(STUDENT_INFO));
}
catch (FileNotFoundException ex) {
System.out.println("\n *** Exception occured while opening "
+ ex.getMessage() + " ***");
System.exit(-1);
}
readData(inputFile, STUDENT_INFO, person1, person2, person3, person4,
person5, person6, person7, person8, person9, person10,
calculatedValues);
System.out.println(calculatedValues.getAverage());
//Get Standard Deviation
standardDeviation(person1, person2, person3, person4, person5, person6,
person7, person8, person9, person10, calculatedValues);
//Print Out the Standard Deviation value
System.out.println(calculatedValues.getStandardDeviation());
for (int i = 0; i < list.size(); i++) {
System.out.println(list.get(i));
}
}
public static void readData(Scanner inputFile, final String STUDENT_INFO,
GradeInfo person1, GradeInfo person2, GradeInfo person3,
GradeInfo person4, GradeInfo person5, GradeInfo person6,
GradeInfo person7, GradeInfo person8, GradeInfo person9,
GradeInfo person10, GradeInfo calculatedValues) {
GradeInfo standardDeviation = new GradeInfo();
int studentID = 0;
String fullName = "";
double testScore = 0, averageScore = 0, scoreHolder = 0;
while (inputFile.hasNext()) {
try {
studentID = inputFile.nextInt();
person1.setStudentID(studentID);
inputFile.nextLine();
fullName = inputFile.nextLine();
person1.setFullName(fullName);
testScore = inputFile.nextDouble();
person1.setTestScore(testScore);
person1.setGrade(testScore);
averageScore = averageScore + testScore;
studentID = inputFile.nextInt();
person2.setStudentID(studentID);
inputFile.nextLine();
fullName = inputFile.nextLine();
person2.setFullName(fullName);
testScore = inputFile.nextDouble();
person2.setTestScore(testScore);
person2.setGrade(testScore);
averageScore = averageScore + testScore;
studentID = inputFile.nextInt();
person3.setStudentID(studentID);
inputFile.nextLine();
fullName = inputFile.nextLine();
person3.setFullName(fullName);
testScore = inputFile.nextDouble();
person3.setTestScore(testScore);
person3.setGrade(testScore);
averageScore = averageScore + testScore;
studentID = inputFile.nextInt();
person4.setStudentID(studentID);
inputFile.nextLine();
fullName = inputFile.nextLine();
person4.setFullName(fullName);
testScore = inputFile.nextDouble();
person4.setTestScore(testScore);
person4.setGrade(testScore);
averageScore = averageScore + testScore;
studentID = inputFile.nextInt();
person5.setStudentID(studentID);
inputFile.nextLine();
fullName = inputFile.nextLine();
person5.setFullName(fullName);
testScore = inputFile.nextDouble();
person5.setTestScore(testScore);
person5.setGrade(testScore);
averageScore = averageScore + testScore;
studentID = inputFile.nextInt();
person6.setStudentID(studentID);
inputFile.nextLine();
fullName = inputFile.nextLine();
person6.setFullName(fullName);
testScore = inputFile.nextDouble();
person6.setTestScore(testScore);
person6.setGrade(testScore);
averageScore = averageScore + testScore;
studentID = inputFile.nextInt();
person7.setStudentID(studentID);
inputFile.nextLine();
fullName = inputFile.nextLine();
person7.setFullName(fullName);
testScore = inputFile.nextDouble();
person7.setTestScore(testScore);
person7.setGrade(testScore);
averageScore = averageScore + testScore;
studentID = inputFile.nextInt();
person8.setStudentID(studentID);
inputFile.nextLine();
fullName = inputFile.nextLine();
person8.setFullName(fullName);
testScore = inputFile.nextDouble();
person8.setTestScore(testScore);
person8.setGrade(testScore);
averageScore = averageScore + testScore;
studentID = inputFile.nextInt();
person9.setStudentID(studentID);
inputFile.nextLine();
fullName = inputFile.nextLine();
person9.setFullName(fullName);
testScore = inputFile.nextDouble();
person9.setTestScore(testScore);
person9.setGrade(testScore);
averageScore = averageScore + testScore;
studentID = inputFile.nextInt();
person10.setStudentID(studentID);
inputFile.nextLine();
fullName = inputFile.nextLine();
person10.setFullName(fullName);
testScore = inputFile.nextDouble();
person10.setTestScore(testScore);
person10.setGrade(testScore);
averageScore = averageScore + testScore;
averageScore = averageScore / 10;
calculatedValues.setAverage(averageScore);
} catch (InputMismatchException ex) {
System.out
.println("\n *** Data doesn't match what the program expected -- "
+ ex.toString() + " ***");
inputFile.close();
System.exit(-1);
}
} // try
}
public static void standardDeviation(GradeInfo person1, GradeInfo person2,
GradeInfo person3, GradeInfo person4, GradeInfo person5,
GradeInfo person6, GradeInfo person7, GradeInfo person8,
GradeInfo person9, GradeInfo person10, GradeInfo calculatedValues) {
double a, b, c, d, e, f, g, h, i, j, standardDeviation;
int x = 0;
double sum = 0;
a = Math.pow(person1.getTestScore() - calculatedValues.getAverage(), 2);
b = Math.pow(person2.getTestScore() - calculatedValues.getAverage(), 2);
c = Math.pow(person3.getTestScore() - calculatedValues.getAverage(), 2);
d = Math.pow(person4.getTestScore() - calculatedValues.getAverage(), 2);
e = Math.pow(person5.getTestScore() - calculatedValues.getAverage(), 2);
f = Math.pow(person6.getTestScore() - calculatedValues.getAverage(), 2);
g = Math.pow(person7.getTestScore() - calculatedValues.getAverage(), 2);
h = Math.pow(person8.getTestScore() - calculatedValues.getAverage(), 2);
i = Math.pow(person9.getTestScore() - calculatedValues.getAverage(), 2);
j = Math.pow(person10.getTestScore() - calculatedValues.getAverage(), 2);
double[] array = { a, b, c, d, e, f, g, h, i, j };
while (x < array.length) {
sum = sum + array[x];
x++;
}
sum = sum / 9;
standardDeviation = Math.sqrt(sum);
calculatedValues.setStandardDeviation(standardDeviation);
}
}
答案 0 :(得分：0)
以下是我认为您正在寻找的循环。顶部循环将使您能够初始化GradeInfo对象并将它们直接添加到arraylist。第二个循环将所有信息放入存储在arraylists中的对象中。您可能需要根据您的具体需求进行调整，但这应该会给您一个良好的开端。
ArrayList<GradeInfo> list = new ArrayList<GradeInfo>();
for(int i = 0; i < 10; i++)
{
GradeInfo gInfo = new GradeInfo();
list.add(gInfo);
}
int testScore;
ArrayList<GradeInfo> list = new ArrayList<GradeInfo>();
for(int x = 0; x < list.size(); x++)
{
list.get(x).setStudentID(inputFile.nextInt());
inputFile.nextLine();
list.get(x).setFullName(inputFile.nextLine();
testScore = inputFile.nextDouble();
list.get(x).setTestScore(testScore);
list.get(x).setGrade(testScore);
averageScore = averageScore + testScore;
}