使用 ID 从数组中删除元素

Question

我在删除其中一个数组中的元素时遇到了一些问题。Students 是我要从中删除元素的数组。我正在按每个 ID 搜索元素。该程序有效，但随后我收到错误消息。我知道我可以使用 indexOf 方法来查找，但这会让我从我拥有的代码从头开始。有没有办法通过从 ID 搜索从数组中删除元素？如果是这样，有没有办法更新数组？

例如

private final ArrayList<Student> students;
students.add(1)//consider nums as ID
students.add(2)
students.add(3)

students = [1,2,3]

students.remove[1]

students = [2,3]

这是我的 removeStudent 方法：

public void removeStudent(int studentId) {

        for (int i = 0; i < students.size(); i++) {
            if (students.get(i).getId() == studentId) {

                System.out.println("Deleted a profile containing information for " + studentId + ":");
//                this.students.remove(studentId);//this is the first one I used that gave me an error but ran
                this.students.removeIf(student -> student.getId().equals(studentId));//this one I got from another response but does not work.
            }
        }
        System.out.println("Could not find profile with that ID");

这是我的 ma​​in 方法::-------------------------------- -------------------------------------------------- -------------------------------------------------- - 所以我尝试使用 remove.Student(studentId) 并且运行良好，但是当我添加学生然后尝试删除他们时，错误再次出现

public static void deleteStudentID() {
        System.out.println("Please enter your student ID to search for your profile");
        int searchId = scanner.nextInt();//asks user to insert an ID
        institution.removeStudent(searchId);//finds the class and searches the Id in array

        showOptions();
    }

Exception in thread "main" java.lang.IndexOutOfBoundsException: Index 1602488517 out of bounds for length 2
    at java.base/jdk.internal.util.Preconditions.outOfBounds(Preconditions.java:64)
    at java.base/jdk.internal.util.Preconditions.outOfBoundsCheckIndex(Preconditions.java:70)
    at java.base/jdk.internal.util.Preconditions.checkIndex(Preconditions.java:248)
    at java.base/java.util.Objects.checkIndex(Objects.java:373)
    at java.base/java.util.ArrayList.remove(ArrayList.java:503)
    at Institution.removeStudent(Institution.java:133)
    at Main.deleteStudentID(Main.java:237)
    at Main.deleteID(Main.java:220)
    at Main.main(Main.java:35)

Answer 1

考虑使用 map 按 ID 存储每个学生：

Map<Integer, Student> students = new HashMap<>();

// returns true if student found and deleted, false otherwise
public boolean removeStudent(int studentId) {
    students.remove(studentId) == null ? false : true;
}

Answer 2

您收到此错误Exception in thread "main" java.lang.IndexOutOfBoundsException: Index 1602488517 out of bounds for length 2 的原因是因为您通过studentId 而不是index 在数组中删除了一个学生：

将removeStudent 更改为：

    public void removeStudent(int studentId) {

      for (int i = 0; i < students.size(); i++) {
          if (students.get(i).getId() == studentId) {

              System.out.println("Deleted a profile containing information for 
                   " + studentId + ":");
              this.students.remove(i);
          }
      }
      System.out.println("Could not find profile with that ID");
    }