stanfordnlp/CoreNLP · error · IndexOutOfBoundsException

Error -- tree does not contain

Error message

Error -- tree does not contain 

What it means

Thrown by the private getNodeNumberHelper while searching for the target-th node (1-based pre-order numbering). If the running counter exceeds the target before it is found, the tree has fewer nodes than the requested index, so the node cannot exist.

Solutions

1. Validate target <= tree.size() (or tree.yield-based node count) before calling.
2. Re-derive node references from the current tree instead of cached node numbers.
3. Catch IndexOutOfBoundsException and treat the node as absent.

Example fix

// before
Tree node = tree.getNodeNumber(target);
// after
if (target <= tree.size()) { Tree node = tree.getNodeNumber(target); }

if (target < 1 || target > tree.size()) return null;

try { return tree.getNodeNumber(target); } catch (IndexOutOfBoundsException e) { return null; }

When it happens

Trigger: Calling tree.getNodeNumber(target) (or treeNumber operations) with a target index larger than the total number of nodes in the tree, typically after the tree was pruned or edited.

Common situations: Storing node numbers/indices from a previous version of a tree and reusing them after tree modification; converting between different tree sizes in parser output post-processing.

Related errors

• t insert tree after the
• ancestor: height cannot be negative
• Bad tree state:
• Can only operate on preterminals
• Can't set Tree labels

AI-assisted analysis of stanfordnlp/CoreNLP@1b7edd19c4 (2026-09-10). Data as JSON: /api/errors/392d94f3600e72cc. Report an issue: GitHub.

Appendix: source

Thrown at src/edu/stanford/nlp/trees/Tree.java:2844

  /**
   * Fetches the {@code i}th node in the tree, with node numbers defined
   * as in {@link #nodeNumber(Tree)}.
   *
   * @param i the node number to fetch
   * @return the {@code i}th node in the tree
   * @throws IndexOutOfBoundsException if {@code i} is not between 1 and
   *    the number of nodes (inclusive) contained in {@code this}.
   */
  public Tree getNodeNumber(int i) {
    return getNodeNumberHelper(new MutableInteger(1),i);
  }

  private Tree getNodeNumberHelper(MutableInteger i, int target) {
    int i1 = i.intValue();
    if(i1 == target)
      return this;
    if(i1 > target)
      throw new IndexOutOfBoundsException("Error -- tree does not contain " + i + " nodes.");
    i.incValue(1);
    for (Tree kid : children()) {
      Tree temp = kid.getNodeNumberHelper(i, target);
      if(temp != null)
        return temp;
    }
    return null;
  }

  /**
   * Assign sequential integer indices to the leaves of the tree
   * rooted at this {@code Tree}, starting with 1.
   * The leaves are traversed from left
   * to right. If the node is already indexed, then it uses the existing index.
   * This will only work if the leaves extend CoreMap.
   */
  public void indexLeaves() {
    indexLeaves(1, false);

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