在 Java 中删除二叉搜索树中的一个节点

Question

I tried making this method which will delete the node recursively, but somehow it says that myRoot will always be null. Can you tell me how?

// To delete a node from the BST
public Node deleteNode(Node myRoot, int toDel) {
    if (myRoot == null) return myRoot;
    else if (toDel < myRoot.data) myRoot.left = deleteNode(myRoot.left, toDel);
    else if (toDel > myRoot.data) myRoot.right = deleteNode(myRoot.right, toDel);
    else {
        // Leaf node
        if (myRoot.right == null && myRoot.left == null) {
            myRoot = null;
        } else if (myRoot.left == null) { // No left child
            myRoot = myRoot.right;
        } else if (myRoot.right==null){ // No right child
            myRoot = myRoot.left;
        }
    }
    return myRoot;
}

NOTE:- This code only deletes the nodes with one child or no child. I am currently working on deleting a node with 2 children so please dont solve that for me.

Answer 1

Per comments on the question, you are asking about a style recommendation from your IDE, related specifically to:

 if (myRoot == null) return myRoot;

Your IDE means that when that particular return statement is executed, myRoot is always null . It is obvious that this is so, because the if ensures that otherwise, that return is not executed. Your IDE is recommending that you change that to

    if (myRoot == null) return null;

Whether you do so is up to you, but personally, I would go with your IDE's advice, because it makes the code slightly clearer.