Return ArrayList 的值

Question

我正在做一个 Java 练习，它告诉我编写一个 toString 方法，但我坚持使用 ArrayList 的 return 值。更多说明，请阅读toString部分的注释。

import java.util.ArrayList;
import java.util.Arrays;

public class Student {
    /** The student's name */
    private String name;
    /** Course codes which the student is enrolled in */
    private ArrayList<String> courses;

    /** Creates a new student with the given name.
     * @name the student's name
     */
    public Student(String name) {
        this.name = name;
        this.courses = new ArrayList<String>();
    }

    /** Enrol in a course.
     * @param course course code of the course being enrolled in. e.g. CSSE2002
     */
    public void addCourse(String course) {
        this.courses.add(course);
    }

    /**
     * Returns the human-readable string representation of this student.
     * The format of the string to return is
     * "'name': courses='courseCodes'" without the single quotes,
     * where 'name' is this student's name and 'courseCodes' is a comma-separated
     * list of this student's enrolled courses.
     * For example, if the student is enrolled several courses:
     * "John Smith: courses=CSSE2002,DECO3801".
     * If the student is enrolled in one course: "John Smith: courses=CSSE2002".
     * If the student is not enrolled in any courses: "John Smith: courses=NO_COURSES".
     * @return string representation of this student
     */
    public String toString() {
        
        Boolean CheckArray = courses.isEmpty();
        if(CheckArray == true){
            return this.name + ":" + " courses=NO_COURSES";
        }else{
            return this.name + ":" + " courses=" + this.courses;
        }
        
    }
}

当运行程序

时，我的测试用例一直出现此错误

我不知道如何乘坐额外的 []，这似乎是一个愚蠢的问题，如果有人能提供帮助，那就太好了。谢谢！

Answer 1

一种可能的解决方案是通过用空字符串替换括号来格式化 this.courses 的输出。

return this.name + ":" + " courses=" + Arrays.toString(this.courses).replace("[", "").replace("]", "");

Answer 2

根据代码注释，测试用例似乎期望输出如下：

John Smith: courses=CSSE2002,DECO3801

您可以使用 String.join 将课程代码与分隔符 ,:

连接起来

return this.name + ":" + " courses=" + String.join(",", this.courses);

Return ArrayList 的值

Return value of ArrayList

java

arraylist

tostring