Java Self-Programmed Single-Linked-List to Linked-List

At least for me, I have a difficult exercise for the university. The challenge is to program a singly linked list with all types of methods. So simple so far, but the challenge is to save these separately linked lists later in the Linked-List. Below you can see my implementation of my singly linked list, which works fine:

public class Liste {

ListenElement first;
ListenElement last;
ListenElement current;
int count;

public Liste() {
    first = null;
    last = null;
    current = null;
    count = 0;
}

// Methods...

      

A singly linked list consists of list items, implemented as follows:

public class ListenElement {

String content;
ListenElement next;

public ListenElement(String content, ListenElement next)
{
    this.content = content;
    this.next = next;
}

//Methods...

      

Here's my problem:

LinkedList<Liste> zeilen = new LinkedList<>();
Liste zeile1 = new Liste();
Liste zeile2 = new Liste();

zeile1.addBehind("Hello");
zeile1.addBehind("World");
zeile2.addBehind("Hello");
zeile2.addBehind("World");

zeilen.add(zeile1);
zeilen.add(zeile2);

System.out.print(zeilen.get(1));
//Printed: Listen.Liste@4aa298b73 instead of Hello World.

      

Thank you in advance for your help!

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1 answer


System.out.print(zeilen.get(1));

      

// Printed: Listen.Liste@4aa298b73 instead of Hello World.

This is the default output Object#toString

. If you need different output from your class Liste

, you need to override toString

to provide that different output.

For example: If you want to Liste#toString

return a toString

comma-delimited list of it:



@Override
public String toString() {
    StringBuffer sb = new StringBuffer(10 * this.count); // Complete guess
    ListenElement el = this.first;
    while (el != null) {
        sb.append(el.content.toString());
        el = el.next;
        if (el != null) {
            sb.append(", ");
        }
    }
    return sb.toString();
}

      

(I am making assumptions about how your list class works based on the code you showed ...)

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