Question

我正在创建一个程序来创建一个名为Student的新类，它设置并获取一些不同的变量。我有一切基本上工作，除非我尝试将正确打印出来的数组元素存储到我的ArrayList中，我得到哈希代码。我肯定会改变一两件小事来修复它，但我最终会在我的智慧中。任何和所有建议都表示赞赏，谢谢！

主：

    Student st = new Student();
Student();
}

public static void Student() {

    System.out.println("Enter the data for student 1 :");
    Student st = new Student();
    Scanner keyboard = new Scanner(System.in);

    String name = keyboard.next();
    double GPA = keyboard.nextDouble();
    boolean enrolled = keyboard.nextBoolean();
    String date = keyboard.next();
 for (int i = 0; i<5; i++){
    Student newStudent = new Student();
    newStudent.setName(name);
    newStudent.setGPA(GPA);
    newStudent.setEnrolled(enrolled);
    newStudent.setDate(date);
    ArrayList <Student> strList = new ArrayList<Student>();
    Student student[] = new Student[5];
    newStudent.getName();
    newStudent.getGPA();
    newStudent.getEnrolled();
    newStudent.getDate();
    newStudent.toString();
    student[i] = newStudent;
    ArrayList myList = new ArrayList();
    myList.add(student[i]);
    System.out.println(student[i].getName());
        System.out.print(student[i].getGPA());
        System.out.print(student[i].getEnrolled());
        System.out.print(student[i].getDate());
     System.out.println(myList);
 }

 }

学生班：

public class Student {

private String name;
private double gpa;
private boolean enrolled;
private String date;

public Student() {

    this.name = "";
    this.gpa = 0.0;
    this.enrolled = false;
    this.date = "none";

}

public Student(String name1) {
    this.name = name1;
    this.gpa = 0.0;
    this.enrolled = false;
    this.date = "none";
}

public void setName(String name) {
    this.name = name;
}

public String getName() {
    return this.name;
}

public void setGPA(double gpa) {
    this.gpa = gpa;
}

public double getGPA() {
    return this.gpa;
}

public void setEnrolled(boolean enrolled) {
    this.enrolled = enrolled;


}

public boolean getEnrolled() {
    return this.enrolled;
}

public void setDate(String date) {
    this.date = date;
}

public String getDate(){
return this.date;
}
 }

Answer 1

Arrays本身不会使用toString方法打印其内容。相反，请使用Arrays.toString(yourArrayVar)或Arrays.deepToString(yourArrayVar)。

此外，不要忘记覆盖toString课程中的Student方法，否则会使用Object#toString，以此格式打印数据（来自JavaDoc）：

getClass（）。getName（）+＆＃39; @＆＃39; + Integer.toHexString（hashCode（））

Answer 2

当您尝试使用此行打印ArrayList

时

System.out.println(myList);

调用

toString()。它会尝试将每个项目转换为String，最终通过toString()调用Student。您不会覆盖toString()，因此您看到的“哈希码”是默认的toString() from Object。

根据需要覆盖toString()以将Student转换为String。

@Override
public String toString()
{
    // Construct a String here that is appropriate for this class.
    // Return it!
}

将数组对象存储到ArrayList中，打印哈希代码

2 个答案: