向链表添加toString方法

Question

我创建了一个链表类来创建一个简单的注册表，在这里我可以从列表中添加和删除学生。然而，我不知道如何创建我的toString方法链表，什么是最好的方式去做这个?提前感谢!

import java.util.*;
public class Registry {

LinkedList<Student> studentList
        = new LinkedList<Student>();
//setting my type parameter


public Registry() {}

public void addStudent(Student aStudent) {}

public void deleteStudent(int studentID) {}

public String toString(){}


public String format() {}

}

Answer 1

LinkedList已经有一个继承自AbstractCollection的toString()方法。

toString
public String toString()
Returns a string representation of this collection. The string representation consists
of a list of the collection's elements in the order they are returned by its iterator,
enclosed in square brackets ("[]"). Adjacent elements are separated by the characters
", " (comma and space). Elements are converted to strings as by String.valueOf(Object).
Overrides:
    toString in class Object
Returns:
    a string representation of this collection

这不是你想要的吗?

Answer 2

目的似乎是列出存储在链表中的所有学生，而不是覆盖链表的toString()。只要你的Student类覆盖了它的toString()方法，你就在你的路上了。打印链表将调用它的toString()方法并给出您想要的结果。

示例类重写toString()

class MyClass 
{
    private int x;
    private int y;
    /* getters and setters  */
    @Override
    public String toString()
    {
        return "MyClass [x=" + x + ", y=" + y + "]";
    }
}

使用

List<MyClass>  myList = new LinkedList<MyClass>();
MyClass myClass = new MyClass();
myClass.setX(1);
myClass.setY(2);
myList.add(myClass);
System.out.println(myList);

打印

[MyClass [x=1, y=2]]

Answer 3

在注册表类中重写toString()

LinkedList将调用成员对象的toString()

来源

Returns a string representation of this collection. The string representation consists of a list of the collection's elements in the order they are returned by its iterator, enclosed in square brackets ("[]"). Adjacent elements are separated by the characters ", " (comma and space). Elements are converted to strings as by java.lang.String.valueOf(java.lang.Object).

Answer 4

1. 你没有创建一个链表类——你创建了一个LinkedList对象。

2. 你想要的是一个toString()方法为您的Registry类

   公共字符串toString() {boolean bracketAdded = false;StringBuffer = new StringBuffer();

   for(Student student : studentList) {
       result.append(bracketAdded ? ", " : "[");
       result.append(student);
       bracketAdded = true;
   }
   result.append("]");
   return result.toString();
   

   }

现在剩下的就是为你的Student类实现一个toString()方法。

Answer 5

我会使用StringBuilder并循环遍历列表。

public String toString(){
  StringBuilder sb = new StringBuilder();
  for (Student s: students){
    sb.append(s.toString()+",");
  }
  return sb.toString();
}

在你的Student类toString()方法中包含你想要的任何信息

编辑:我注意到在另一个响应中，链表上的toString()正在使用String.valueOf()。实际上，在大多数情况下我更喜欢这样，因为它会处理空值，当然，除非你想知道空值什么时候出现在这个列表中。

所以不是:

sb.append(s.toString()+",");

你可以使用:

sb.append(String.valueOf(s),"+");