Код не уронит студентов с курса [Java]

Question

Та же проблема, что и this post, но я думаю, что я приближаюсь к ее решению.

В моем коде, в двух словах, есть два курса, и я должен отбросить несколько учеников от каждого из них, а затем полностью очистить второй курс. Этот код выполняется с использованием двух классов.

Это то, что я до сих пор:

/* 
Program description: 
Starting with listing 10.5 and 10.6 below, you are to modify the two source 
files to: 

Course.java: 


add method increaseArray(). 
Increase the array when students are added by 1, (hint utilize 
System.arraycopy method). Then add the student to the last location. I 
would suggest you set the size of the “students” array to a size initially 
of zero, so when the any student is added, your code to increase the 
array will be triggered. 

add method dropStudent(). 
Drop student would need to find the String match by iterating on the 
students array using the .equals String method. When a match is found, 
remove that entry by assigning the next student into the match location, 
and do for all the remaining students (effectively shift remaining 
students by one). Also you would have also decrement the 
numberOfStudents count. 

add method clear(). 
Iterating on the students array assign all to null and set the 
numberOfStudents count to 0. 
TestCourse.java: 
You need to test your new methods; this is done by modifying listing 10.5 to 
meet the requirements of assignment which are: 

Create a two courses 
Add six students to the first, three students to the second 
Remove the first two student from course one 
Remove the second student from course two 
Display students in both classes 
Clear the second course 
Display students in both classes 


Add a static method to TestCourse that handles printing the students in a 
class. This method receives the reference of the course and the course 
number. This way, you just call the method to print out the students. 
*/ 

public class Course { 
private String courseName; 
private String[] students = new String[100]; 
private int numberOfStudents; 

public Course(String courseName) { 
    this.courseName = courseName; 
} 

public void addStudent(String student) { 
    students[numberOfStudents] = student; 
    numberOfStudents++; 
} 

public String[] getStudents() { 
    return students; 
} 

public int getNumberOfStudents() { 
    return numberOfStudents; 
} 

public String getCourseName() { 
    return courseName; 
} 

public void dropStudent(String student) { 

    int IndexOfStudentToDrop = -1; 

    for (int i = 0; i < numberOfStudents; i++) { 
     if (students[i].equalsIgnoreCase(student)) { 
      IndexOfStudentToDrop = i; 
      if (IndexOfStudentToDrop != -1) { 
       for (i = IndexOfStudentToDrop; i < numberOfStudents; i++) 
        students[i] = students[i+1]; 
      } // end if found 
      // decrement number of students by 1 
      numberOfStudents--; 
     } 
    } 

} 

public void clear() { 

    for (int i = 0; i < numberOfStudents; i ++){ 
     students [i] = null; 
    } 
    numberOfStudents = 0; 

} 

public void increaseArray() { 
    if (numberOfStudents >= students.length) { 
     String[] temp = new String[students.length * 2]; 
     System.arraycopy(students, 0, temp, 0, students.length); 
     students = temp; 
    } 



} // end of increaseArray() 

public String toString() 
{ 
    String output = ""; 
    output += getCourseName()+ (getNumberOfStudents() + "students"); 
     for (int i = 0; i < getNumberOfStudents(); i++) { 
       output += "\n("+ (i + 1)+")"+ students [i]; 
      } 
    return output; 

} 
} 

и

public class TestCourse { 
public static void main(String[] args) { 

    // create two courses 
    Course course1 = new Course("Data Structures"); 
    Course course2 = new Course("Database Systems"); 

    // introduce the program 
    System.out.println("Creating Two Courses"); 
    System.out.println("Adding 6 students to course 1"); 
    System.out.println("Adding 3 students to course 2"); 


    // add six students to course1 
    course1.addStudent("\n1: Tom Servo"); 
    course1.addStudent("\n2: Joel Robinson"); 
    course1.addStudent("\n3: Mike Nelson"); 
    course1.addStudent("\n4: Pearl Forrester"); 
    course1.addStudent("\n5: TV's Frank"); 
    course1.addStudent("\n6: Zap Rowsdower"); 
    System.out.println(); 
    System.out.println(); 




    // add three students to course2 
    course2.addStudent("\n1: Tom Servo"); 
    course2.addStudent("\n2: Crow T. Robot"); 
    course2.addStudent("\n3: Zap Rowsdower"); 
    System.out.println(); 
    System.out.println(); 



    // output to the console 
    System.out.println ("Number of students in Course 1: " + course1.getNumberOfStudents() + " Students are: "); 
    String [] students = course1.getStudents(); 

    for (int i = 0; i < course1.getNumberOfStudents(); i++) 
     System.out.print(students[i]); 


    System.out.println(); 
    System.out.print("Number of students in Course 2: " + course2.getNumberOfStudents() + " Students are: "); 
    String [] students1 = course2.getStudents(); 

    for (int i = 0; i < course2.getNumberOfStudents(); i++) 
     System.out.print(students1[i]); 

    // output to the console how many students will be dropped from each class 
    System.out.println("dropping 2 students from course 1"); 
    System.out.println("dropping 1 student from course 2"); 


    // drop some students. 
      course1.dropStudent("Tom Servo"); 
      course1.dropStudent("Joel Robinson"); 
      System.out.println ("\nNumber of students in Course 1: " + course1.getNumberOfStudents() + " Students are: "); 

      course2.dropStudent("Crow T. Robot"); 
      System.out.println("\nNumber of students in Course 2: " + course2.getNumberOfStudents() + " Students are: "); 

    // clear course2, but keep course1 as it currently stands 
      System.out.println("\nclearing course 2 course 2"); 
      course2.clear(); 

      System.out.println("\nNumber of students in Course 1: " + course1.getNumberOfStudents() + " Students are: "); 
      System.out.println("\nNumber of students in Course 2: " + course2.getNumberOfStudents() + " Students are: "); 
    } 

} 

Это то, что вывод должен выглядеть следующим образом:

Creating Two Courses 
Adding 6 students to course 1 
Adding 3 students to course 2 

Number of students in Course 1: 6 Students are: 
1: Tom Servo 
2: Joel Robinson 
3: Mike Nelson 
4: Pearl Forrester 
5: TV's Frank 
6: Zap Rowsdower 

Number of students in Course 2: 3 Students are: 
1: Tom Servo 
2: Crow T. Robot 
3: Zap Rowsdower 

dropping 2 students from course 1 
dropping 1 student from course 2 

Number of students in Course 1: 4 Students are: 
1: Mike Nelson 
2: Pearl Forrester 
3: TV's Frank 
4: Zap Rowsdower 

Number of students in Course 2: 2 Students are: 
1: Tom Servo 
2: Zap Rowsdower 

clearing course 2 course 2 

Number of students in Course 1: 4 Students are: 
1: Mike Nelson 
2: Pearl Forrester 
3: TV's Frank 
4: Zap Rowsdower 

Number of students in Course 2: 0 Students are: 

Но это то, что происходит вместо этого:

Creating Two Courses 
Adding 6 students to course 1 
Adding 3 students to course 2 




Number of students in Course 1: 6 Students are: 

1: Tom Servo 
2: Joel Robinson 
3: Mike Nelson 
4: Pearl Forrester 
5: TV's Frank 
6: Zap Rowsdower 
Number of students in Course 2: 3 Students are: 
1: Tom Servo 
2: Crow T. Robot 
3: Zap Rowsdowerdropping 2 students from course 1 
dropping 1 student from course 2 

Number of students in Course 1: 6 Students are: 

Number of students in Course 2: 3 Students are: 

clearing course 2 course 2 

Number of students in Course 1: 6 Students are: 

Number of students in Course 2: 0 Students are: 

Как вы можете видеть, мой код не отбрасывает студентов, когда мне это нужно (хотя очистка не кажется проблемой). Я знаю, что мое форматирование испорчено, но это не моя главная проблема, и я мог бы это исправить самостоятельно. Помимо форматирования, меня бросают ученики - моя единственная проблема, и если бы я мог просто помочь с этим, я могу взять это отсюда.

Answer 1

Причина этого не работает, состоит в следующем: Вы ставите строки как 1: Tom Servo с номером, и пытается удалить их, как course1.dropStudent("Tom Servo");

Если вы либо удалить 1: при добавлении Student, или вы бы попробуйте удалить их как:

course1.dropStudent("1: Tom Servo"); 

Я уверен, что это сработает.