Question

你好，我有一个关于如何解决这个程序的问题。我已经完成了这个大纲，但我需要帮助完成它。谢谢大家的意见！

问题。

班级Roster的对象代表课程的特定部分。名单上有一系列students，一个int numStudents，表示该部分中有多少学生，int stopPoint表示该部分中可能有的学生人数，还有一个course，说明这个名单的哪个部分是。

请注意，学生在数组中没有任何特定顺序，但它们将位于数组的第一个numStudents元素中。

代码：

public class Roster {
    Student [ ] students;
    int numStudents;
    int stopPoint;
    Course course;

    /**
     * The constructor for this class.
     * Initialize this roster so that it is empty, i.e., holds no students,
     *  but so that it can hold up to stopPoint students
     *   and so that it has the given stop point and course
     */
    public Roster(int stopPoint, Course course){
    this.stopPoint = stopPoint;
    this.course = course;
    this.students = new Student [stopPoint];
    }

    /**
     * toString is a method every class has.  It returns a string 
     * that represents the object for printing
     */
    public String toString( ){
    String res = "";
    for(int j = 0; j < numStudents; j++){
        res = res + "\n" + students[j].toString();
    }
    return course + " " + numStudents + "/" + stopPoint+res;
    }

    /**
     * isFull returns true if and only if the number of students in it is 
     *   at the stopPoint
     */
    public boolean isFull( ){
    return false;   // replace this line with your code
    }

    /**
     * add given student to this roster
     * if student already on roster or numStudents already == stopPoint, 
     *   do not change roster and return false
     * worst case O(1) - add the new Student at the end of the array
     * @return true if successful, else false
     */
    public boolean addStudent(Student student){

    return false; // replace this line with your code

    }


    /**
     * returns true if and only if the student is on this roster.
     */
    public boolean findStudent(Student student){

    return false; // replace this line with your code

    }

    /**
     * Remove given student from this roster. 
     * If student is not on this roster do not change roster and return           false
     * @return true if successful, else false
     */
    public boolean dropStudent(Student student){

    return false; // replace this line with your code

    }

}

Answer 1

我建议你使用List而不是数组来保存学生，然后你拥有的其他方法只会委托给这个列表。

public Roster(int stopPoint, Course course){
this.stopPoint = stopPoint;
this.course = course;
this.students = new ArrayList<Students>(stopPoint);
}


public String toString( ){
String res = "";
for(Student s: students){
    res = res + "\n" + s.toString();
}
return course + " " + numStudents + "/" + stopPoint+res;
}


public boolean isFull( ){
return students.size() == stopPoint;
}


public boolean addStudent(Student student){
if(!student.contains(student) && !isFull()){
    students.add(student);
    return true;    
}
    return false;

}

public boolean findStudent(Student student){
return students.contains(student);
}

public boolean dropStudent(Student student){
return students.remove(student); 
}

java的名册程序

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