不能从 **静态上下文** 引用非静态方法.这里的静态内容是什么?

问题描述

我正在编写一个程序来从文本文件(仅包含整数)中获取输入，将其放入链表并显示链表.这是我的代码:

I am writing a program to get input from a text file (only contain integers), put it into linked list and display the linked list. Here is my code:

import java.util.Scanner;
import java.io.File;
import java.io.FileNotFoundException;

class Node{
    int value;
    Node next;
    Node(){
        next = null;
    }
}


public class ReverseLL{
    public static void main(String[] args) throws FileNotFoundException{
        Scanner in = new Scanner(new File("input.txt"));
        Node head = null;
        Node tail = null;
        while(in.hasNextInt()){
            Node ptr = new Node();
            ptr.value = in.nextInt();
            if(head == null){
                head = ptr;
                tail = ptr;
            }else{
                tail.next = ptr;
            }
            tail = ptr;
        }
        display(head);
        in.close();
    }

    static void display(Node head){
        while(head!=null){
            System.out.print(head.value + " " + "\n");
            head = head.next;
        }
    }

}

在我将显示方法更改为静态后，它现在可以工作了.但是在我改成静态之前.错误说非静态方法 display(Node) 不能从 **static 上下文中引用 我阅读了一些关于静态和非静态的文档.要调用非静态，我需要实例化一个实例，然后像 instance.method 一样调用.要调用静态方法，您可以像class.method"一样调用.我的问题是基于我的程序.我没有在其他类中创建方法，为什么要改为静态方法?什么是所谓的静态内容?谢谢你给我解释.

It works now after I changed the display method to be static. However before I changed to static. The error said non-static method display(Node) cannot be referenced from a **static context I read some document about the static and no-static. To call a no-static, I need to instantiate an instance then call like instance.method. To call static method, you can call like "class.method". My question is based on my program. I did not create the method in other class, why I need to change to static method? What is the so called static content? Thank you for explaining it to me.

推荐答案

您的主方法是静态上下文，您正试图从中调用非静态方法 display().即使在同一个班级，那也行不通.要使显示方法非静态，您必须这样做.

Your main-method is the static context, and you are trying to call the non-static method display() from it. That doesn't work even if it is in the same class. To have the disply method non-static you have to do this.

public static void main(String[] args) throws FileNotFoundException{
    ReverseLL r = new ReverseLL();
    r.display(head);

}

public void display(Node head){
    ...
}

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