Generic class using generic parameter

Question

I want to achieve the following.

I have a generic class Node<K,T,V> which looks as follows:

public class Node<K,T,V>{

/**
 * @return the key
 */
public K getKey() {
    return key;
}
/**
 * @param key the key to set
 */
public void setKey(K key) {
    this.key = key;
}
// etc...

Now I want to have a class Tree which operates on Nodes with arbitrary parametrized types:

public class Tree <Node<K,V,T>> {
   public void insert(Node<K,V,T> node){
      K key = node.getKey();
      // do something...
   }
// ... etc...
}

This, however, does not work, since Eclipse tells me the line public class Tree <Node<K,V,T>> does not look good :) If I change it to

public class Tree <Node> {

It tells me that the type Node is hiding the type Node. How can I achieve that from the Tree class I can properly access the types K, V and T?

I'm pretty sure this question has been answered a bazillion times. I did, however, not find anything at all - so sorry for that!!!

Cheers.

Thank you @ChristianSt.! And @Shail016, thank you for the solution. I went for the second solution. It does not read as nicely as my initial try, but it works! — Filex
– Filex, Commented Jul 9, 2014 at 10:51

Shailesh Aswal · Accepted Answer · 2014-07-09 10:40:44Z

6

you can change your tree to :

class Tree<K, T, V> {
    public void insert(Node<K, T, V> node) {
        K key = node.getKey();
        // do something...
    }
    // ... etc...
}

or if you want to bind it to Node,

class Tree2<N extends Node<K, T, V>, K, T, V> {
    public void insert(N node) {
        K key = node.getKey();
        // do something...
    }
    // ... etc...
}

edited Jul 9, 2014 at 10:40

answered Jul 9, 2014 at 10:34

Shailesh Aswal

6,8521 gold badge22 silver badges28 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

EpicPandaForce Over a year ago

I was going to write the second one but was too slow, nicely done :) Although it'd be better to maintain the <K,V,T> parameter order.

Shailesh Aswal Over a year ago

thanks, edited the order for Node<K,T,V> as defined by the op

Collectives™ on Stack Overflow

Generic class using generic parameter

1 Answer 1

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related