how to instance a non-static method, that has a wired object and is from another file

I'm having trouble calling a non-static method from an another file. My main file is called jroff.java, and the other file (which has the two methods I need) is called linkedqueue.java

In linkedqueue.java I have the following code:

class linkedqueue <item_t> {

   private  class node{
      item_t item;
      node link;
   }

   private  node front = null;
   private  node rear = null;

   public  boolean empty (){
      return front == null;
   }

   public void insert (item_t any) {
      node temp = new node();
      t开发者_JS百科emp.item = any;
      temp.link = null;
      if(rear == null) front = temp;
              else rear.link = temp;
  rear = temp;
   }

 public item_t remove (){
      item_t value;
      if (empty ()) throw new NoSuchElementException ();
      value = front.item;
      front = front.link;
      if(front == null) return null;
                    else return value;
   }

}

this is how i'm trying to run insert in my main file:

 for (String word: words) linkedqueue.insert(word);

I got the file name thing right, but how exactly do I make an instance of something like this? Here is where I use insert:

   String value;
   while(value != null){
       value = linkedqueue.remove().toString();

remove returns a item_t, and i want that in a string. the last node will have a value of null, thats when the loop should stop.

Thanks for the help.

There is no such thing as calling a method from another file. In Java you are defining classes and you can interact with the non-static methods of a class by creating an instance of this class with the new keyword.

I highly recommend either reading Java in a Nutshell or doing the Java tutorial. It will make things a lot clearer.

There are a couple issues with this code:

1. The naming convention in Java is to have class names starting with a capital letter, and variables starting with a lowercase. This is important here because it might be a source of confusion for you.

2. linkedqueue.insert(word); looks like a legal command, but you are in fact trying to call a non-static method on a Class object. This is not possible. You should create an instance of the class before trying this:

   linkedqueue lq = new linkedqueue();
   

   and then perform all of your actions on lq.

3. Based on your own spec, the following will throw a NullPointerException by design, if it ever got past a few issues:

     String value;
       while(value != null){
         value = linkedqueue.remove().toString();
      }
 

• a variable in a method needs to be initialized before it is used.
• if it were initialized to null, your body of your while will never execute. Consider a do{}while() instead.