我是我大学 Java 课程的助教，今天有一个学生在实验室遇到了一个非常奇怪的问题。我查看了大约一个小时，让实验室的其他 TA 做同样的事情，但我们找不到问题。
实际上，我们在这里所做的是创建 3 个数组，将它们传递给一个新方法。在新方法中修改这些数组的值并返回到原始方法。我们没有使用 return 语句将任何数组返回给原始方法。相反，我们正在利用，我只能将来自 C 背景的东西描述为传递引用。但是，在返回到原始方法时，值已更改为一些不正确的值。
在这个特定示例中，我们有三个数组，分别称为：“exams”、“quizzes”和“labs”。这些数组中的每一个的大小为 1,000，并被初始化为 -1。在第一个方法“calcGrade”中，我们创建这些数组并初始化它们。然后我们将所有三个数组传递给第二种方法，该方法捕获用户拥有的考试、测验和实验室的数量，然后将实际的考试、测验和实验室成绩值存储到数组中。
方法 1 (calcGrade)
exams quizzes labs
-1 -1 -1
-1 -1 -1
-1 -1 -1
-1 -1 -1
. . .
. . .
. . .
方法 2 (getScores)
exams quizzes labs
90 80 90
-1 80 90
-1 -1 -1
-1 -1 -1
. . .
. . .
. . .
返回方法 1 (calcGrades)
exams quizzes labs
80 90 90
-1 -1 90
-1 -1 -1
-1 -1 -1
. . .
. . .
. . .
谁能想到这可能发生的任何原因？老实说，我被难住了，我不希望他因为似乎没有错的事情而失去信誉……
这是代码（请注意，其中有几个 println 语句用于调试目的）：
import java.util.Scanner;
public class CSE1341Grade{
public static void main(String [] args){
Scanner input = new Scanner(System.in);
System.out.println("What is your first name? ");
String first = input.nextLine();
System.out.println("What is your last name? ");
String last = input.nextLine();
calcGrade(first, last);
}
public static void calcGrade(String first, String last){
int base = 1000;
int[] quizzes = new int [base];
int[] exams = new int [base];
int[] labs = new int [base];
for(int x = 0; x < base; x++)
{
quizzes[x] = -1;
exams[x] = -1;
labs[x] = -1;
}
int[] countarr = getScores(quizzes, exams, labs);
System.out.println("EXAMS:");
for(int x = 0; x < countarr[0]; x++)
System.out.println(exams[x]);
System.out.println("QUIZ:");
for(int x = 0; x < countarr[1]; x++)
System.out.println(quizzes[x]);
System.out.println("LABS:");
for(int x = 0; x < countarr[2]; x++)
System.out.println(labs[x]);
for(int x = 0; x < countarr.length; x++)
System.out.println(countarr[x]);
//System.out.println("----");
double examAvg =0.0;
for(int i=0;i<countarr[0];i++){ //adding together scores
examAvg+=exams[i];
//System.out.println(examAvg);
}
//System.out.println("----");
double quizAvg=0.0;
for(int i=0;i<countarr[1];i++){ //adding together scores
quizAvg+=quizzes[i];
//System.out.println(quizAvg);
}
//System.out.println("----");
double labAvg=0.0;
for(int i=0;i<countarr[2];i++){ //adding together scores
labAvg+=labs[i];
//System.out.println(labAvg);
}
examAvg = examAvg/countarr[0];
quizAvg = quizAvg/countarr[1];
labAvg = labAvg/countarr[2];
double totalAverage = (.5 * examAvg) + (.35 * quizAvg) + (.1 *labAvg) + 5.0;
System.out.println("Total Score: " +totalAverage);//display average
String grade = "";
if (totalAverage >= 90)
grade = "A";
else if (totalAverage >= 80)
grade ="B";
else if (totalAverage >= 70)
grade = "C";
else
grade = "F";
System.out.println(first + " " + last + " your grade is a: " + grade); //letter grade
}
public static int [] getScores(int [] exams, int [] quizzes, int [] labs){
Scanner input = new Scanner(System.in);
int [] countArray = new int[3]; //holding numbers of exams quizzes labs
System.out.println("How many exam grades do you have? ");
countArray[0] = input.nextInt();
System.out.println("How many quiz grades do you have? ");
countArray[1] = input.nextInt();
System.out.println("How many lab grades do you have?" );
countArray[2] = input.nextInt();
System.out.println(countArray[0] + ", " + countArray[1] + ", " + countArray[2]);
for(int counter = 0; counter < countArray[0]; counter++){ //every exam score
System.out.printf("Enter Exam" + " " + (counter + 1) + " " + "score: ");
exams[counter]=input.nextInt();
System.out.println(exams[counter]);
}
System.out.println("----");
for(int counter = 0; counter < countArray[1]; counter++){ //every quiz score
System.out.printf("Enter Quiz" + " " + (counter + 1) + " " + "score: ");
quizzes[counter]=input.nextInt();
System.out.println(quizzes[counter]);
}
System.out.println("----");
for(int counter = 0; counter < countArray[2]; counter++){ //every lab score
System.out.printf("Enter Lab" + " " + (counter + 1) + " " + "score: ");
labs[counter]=input.nextInt();
System.out.println(labs[counter]);
}
System.out.println("----");
System.out.println("EXAMS:");
for(int x = 0; x < countArray[0]; x++)
System.out.println(exams[x]);
System.out.println("QUIZ:");
for(int x = 0; x < countArray[1]; x++)
System.out.println(quizzes[x]);
System.out.println("LABS:");
for(int x = 0; x < countArray[2]; x++)
System.out.println(labs[x]);
System.out.println("************************");
return countArray; //return back to calc grade
}
}