java - 无法将主类中的字符串值设置为setter

Question

public class StudentTest{

  public static void main(String args[]){

    UnderGrad uG1 = new UnderGrad();
    uG1.setName("John");
    uG1.setMatric("0192345");

    System.out.println("Undergarduate Student Info");
    uG1.setCourse(new Course("CS1103",3));
    uG1.setCourse(new Course("IT4504",3));
    uG1.displayStudentInfo();

    System.out.println(" ");

    PostGrad pG1 = new PostGrad();
    pG1.setName("Sam");
    pG1.setMatric("G015466");
    pG1.setResearch("Empirical Software Engineering");
    pG1.setResearch("Data Mining");
    System.out.println("Postgrad Student Info");
    pG1.displayStudentInfo();
  }
}

public class Course{
  private String courseName;
  private int crhour;

  public Course(String n, int c){
    courseName = n;
    crhour = c;
  }

  public void setCourseName(String course){
    courseName = course;
  }

  public String getCourseName(){
    return courseName;
  }

  public void setCreditH(int c){
    crhour = c;
  }
}

public class Student{

  private String matric ="-matric required-";
  private String name="-name required-";

  public Student(){
  }

    public void setName(String n){
      if (n.matches("[a-zA-Z]+") == false)
        System.out.println("Invalid Name");
      else
        name = n;
    }
    public String getName(){
    return name;}


  public void setMatric(String m){
    matric = m;}
  public String getMatric(){
    return matric;}
}

      public class UnderGrad extends Student{
    private Course courseList[];
    private int index = 0;

    public UnderGrad(){
      Course courseList[] =new Course[7];}

  public void setCourse(Course courseName){
    //Course courseList[]= new Course[2];
    }

  public Course[] getCourse(){
  return courseList;}

  public void displayStudentInfo(){

    System.out.println("Name: "+getName());
    System.out.println("Matric: "+getMatric());
    System.out.println("Course List: "+getCourse());
      }}

  public class PostGrad extends Student{
    private String researchArea[];
    private int index = 0;

    public PostGrad()
 {
 researchArea = new String[5];
 }

  public void setResearch(String research){
      for(index=0;index<2;index++){
        researchArea[index]=research;}
    }

  public String[] getResearch(){
  return researchArea;}

  public void displayStudentInfo(){

    System.out.println("Name: "+getName());
    System.out.println("Matric: "+getMatric());
    System.out.println("Research List: "+getResearch());
      }}

输出:

本科生信息

姓名:约翰

矩阵:0192345

类(class)列表:空

研究生信息

姓名:山姆

矩阵:G015466

类(class)列表:[Ljava.lang.String;@2ac9fefa

问题是我无法获取类(class)和研究的 String 值。我该怎么办？我应该使用 super 引用吗？

Answer 1

这里:

System.out.println("Course List: "+getCourse());

您正在打印字符串数组返回的默认toString()。不要那样做。遍历数组并打印每个项目，或者使用 java.util.Arrays.toString(...)。

System.out.println("Course List: "+ java.util.Arrays.toString(getCourse()));

您还需要为您的 Course 类提供一个有效的 toString() 方法，该方法返回 courseName 以及可能的学分。另外，我会将类(class)字段更改为类(class)或类(class)列表，以反射(reflect)它并不代表一门类(class)，而是代表一组类(class)。同样，getter 方法应该反射(reflect)字段名称的更改。