# How to make a two-way list with only the number of elements, Java.

• There's a DDS DoubleNode, which is a two-way list:

``````public class DoubleNode {
public int value;
public DoubleNode prev;
public DoubleNode next;
public DoubleNode(int value, DoubleNode prev, DoubleNode next) {
this.value = value;
this.prev = prev;
this.next = next;
}
``````

But what I'm trying to do is build a number like this, knowing only the number of elements in it (the meanings of the elements are randomly chosen). But I want to build a sensual approach, so I'm gonna put it this way:

``````    public static DoubleNode doubleNodeGenRec (int length) {
return (length == 0) ? null : new DoubleNode((int)(Math.random()*10), null, doubleNodeGenRnd(--length));
}
``````

to refer the reference to `DoubleNode prev;`?

Turns out that Node is built on on the same side, because the method is simply null, and as a result, it's just a tied list.

• ``````public DoubleNode(int value) {
this.value = value;
}

public static DoubleNode doubleNodeGen(int length) {
return doubleNodeGenRec(length, null);
}

private static DoubleNode doubleNodeGenRec(int length, DoubleNode prev) {
if (length == 0) {
return null;
}

int value = (int) (Math.random() * 10);
DoubleNode node = new DoubleNode(value);
node.prev = prev;
node.next = doubleNodeGenRec(length - 1, node);
return node;
}
``````

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