Question

我无法理解代码有什么问题。该方法返回Exam类型的对象数组。方法readAllExams从Scanner中提取标记并使用它们创建Exam对象。 Exam对象以数组形式返回。请帮忙吗？

public Exam(String firstName, String lastName, int ID, String examType, int score) {
    this.firstName = firstName;
    this.lastName = lastName;
    this.ID = ID;
    this.examType = examType;
    this.score = score;
}

public static Exam[] readAllExams(Scanner s) {
    String firstName = "";
    String lastName = "";
    int ID = 0;
    String examType = "";
    int score = 0;

    Exam[] object = new Exam[5];

    while(s.hasNext()) {
        firstName = s.next();
        lastName = s.next();

        if(s.hasNextInt()) {
            ID = s.nextInt();
        } else {
            s.next();
        }

        examType = s.next();
        if(s.hasNextInt()) {
            score = s.nextInt();
        }

        object[] = new Exam(firstName, lastName, ID, examType, score);
        return object;
    }   
}

Answer 1

我认为你的代码应该是：

public static Exam[] readAllExams(Scanner s)
{
    String firstName = "";
    String lastName = "";
    int ID = 0;
    String examType = "";
    int score = 0;

    Exam[] object = new Exam[5];

    int index = 0; //new added code
    while(s.hasNext())
    {
      //  ........... your code ..........

        object[index++] = new Exam(firstName, lastName, ID, examType, score); 
    }
    return object; //return should be out of while loop to return an array

}

Answer 2

object[]不是索引数组的有效方法。

为了分配数组的元素，您需要知道哪个元素。例如，object[0]是第一个元素。 object[4]是第5个元素。 object[index]是index包含0的第一个元素，index包含1的第二个元素，index包含2的第三个元素等等...

填写数组时，常见的事情是保留一个计数器，存储您当前正在填写的索引 - 例如:(为简洁起见，删除了大部分代码）

int currentIndex = 0;
while(...) {
    ...
    object[currentIndex] = ...;
    currentIndex = currentIndex + 1; // or currentIndex += 1; or currentIndex++;
}

返回一个对象数组的方法有什么问题？

2 个答案: