具有通用参数java的函数

Question

I have a tree of objects T , declared as

 public class Tree<T> {

    private Node<T> root;

    public Tree(T rootData) {
        root = new Node<T>();
        root.data = rootData;
        root.children = new ArrayList<Node<T>>();
    }

    public static class Node<T> {
        private T data;
        private Node<T> parent;
        private List<Node<T>> children;
    }
}

and want to add a function keepBranch , wich reduces the tree to one of its branch.

But I need keepBranch to take an object T as a parameter , to select the branch.
Something like

public void keepBranch(<T> param) {

        for (Node<T> node : this.root.children) {
            if (param.equals(node.data)) {
                this.root = node;
            }
        }
}

Is there a way to do this? Or am I doing it wrong?

Answer 1

Change the parameter type to T . But your comparison is wrong, you compare a value to a node. Change is so that the node's value is being compared to param :

public void keepBranch(T param) {
    for (Node<T> node : this.root.children) {
        if (param.equals(node.data)) {
            this.root = node;
        }
    }
}

Answer 2

It should be T param instead of <T> param :

public void keepBranch(T param) {

        for (Node<T> node : this.root.children) {
            if (param.equals(node.data)) {
                this.root = node;
            }
        }
}

EDIT

As said in comments, it should be param.equals(node.data) instead of node == param

Documentation : Lesson: Generics (Updated)