使用 for 循环和用户输入将元素添加到 LinkedList

Question

我正在尝试使用 for 循环将元素添加到 LinkedList 中，每当我打印列表时，它只包含我的一个输入，并将其放在每个索引中。

我有一种感觉，问题出在我的 toString 方法或我的 Student 构造函数上，但似乎无法弄清楚。

感谢任何和所有的帮助。谢谢！

import java.util.*;
public class Student {
private static String name;
private static String address;
private static double GPA;
static LinkedList<Student> stu = new LinkedList<Student>();
static Scanner scanner = new Scanner(System.in);

public Student(String name, String address, double GPA) {
Student.name = name;
Student.address = address;
Student.GPA = GPA;
}
public String getName() {
return Student.name;
}
public String getAddr() {
return Student.address;
}
public double getGPA() {
return Student.GPA;
}
public static void main(String [] args) {
for (int i = 0; i <= 2; i++) {
System.out.println("Enter the student's name: ");
name = scanner.next();
System.out.println("Enter the student's address: ");
address = scanner.next();
System.out.println("Enter the student's GPA: ");
GPA = scanner.nextDouble();
stu.addLast(new Student(name, address, GPA));
}
System.out.println(stu);
}
@Override
public String toString() {
String str = "Name: " + getName() + "nAddress: " + getAddr() + "nGPA: " + getGPA()+ "nn";
return str;
}
}

安慰

Enter the student's name: 
Jim
Enter the student's address: 
111Ave
Enter the student's GPA: 
2.3
Enter the student's name: 
Joe
Enter the student's address: 
222Ave
Enter the student's GPA: 
3.0
Enter the student's name: 
Jack
Enter the student's address: 
333Ave
Enter the student's GPA: 
3.4
[Name: Jack
Address: 333Ave
GPA: 3.4
, Name: Jack
Address: 333Ave
GPA: 3.4
, Name: Jack
Address: 333Ave
GPA: 3.4
]

Answer 1

属性name、address和GPA是static的，这意味着可以从您创建的所有学生对象访问它们。因此，当您创建一个新的学生对象并调用它的构造函数时，您可以更改之前创建的所有其他学生对象的name、address和GPA的值。

要解决您的问题，您需要从name、address和GPA的声明中删除static关键字。

现在剩下的就是改变你访问变量的方式。请注意，每当您想使用属性name时，您如何使用Student.name？这仅在name是静态的"akaname对所有Students都相同"时才有效。我们现在想使用当前学生的name而不是所有学生，所以我们应该使用this.name而不是Student.name。同样，将Student.GPA更改为this.GPA，将Student.address更改为this.address。

此外，你不能只使用属性name、address和GPA在 main 中没有对象"因为它们不再static"，所以你需要在 main 中声明name、address和GPA，请注意这些变量与Student类中的变量属性无关。 请参考此代码以更好地理解，对不起我的糟糕解释。

import java.util.*;
public class Student {
private String name;
private String address;
private double GPA;
static LinkedList<Student> stu = new LinkedList<Student>();
static Scanner scanner = new Scanner(System.in);

public Student(String name, String address, double GPA) {
this.name = name;           //this.name instead of Student.name
this.address = address;     //this.address instead of Student.address
this.GPA = GPA;             //this.GPA instead of Student.GPA
}
public String getName() {
return this.name;           //similarly
}
public String getAddr() {
return this.address;        //similarly
}
public double getGPA() {
return this.GPA;            //similarly
}
public static void main(String [] args) {
for (int i = 0; i <= 2; i++) {
System.out.println("Enter the student's name: ");
//notice here. "name" can be changed to anything, "sname" for example
//this variable is just to store the input, it's not related to the name
//attribute in the class
String name = scanner.next();
System.out.println("Enter the student's address: ");
//same goes for address and GPA
String address = scanner.next();
System.out.println("Enter the student's GPA: ");
double GPA = scanner.nextDouble();
//use the input taken above to create a new student by calling the constructor
stu.addLast(new Student(name, address, GPA));
}
System.out.println(stu);
}
@Override
public String toString() {
String str = "Name: " + getName() + "nAddress: " + getAddr() + "nGPA: " + getGPA()+ "nn";
return str;
}
}