title: non-static method cannot be referenced from a **static context**. What is static content here?
body: <p>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:</p>
  
  <pre><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;
          }
      }
  
  }
  </code></pre>
  
  <p>It works now after I changed the display method to be <strong>static</strong>. However before I changed to static. The error said <strong>non-static method display(Node) cannot be referenced from a **static context</strong> 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 <strong>static content</strong>? Thank you for explaining it to me.</p>