JetBrains/intellij-community · error · NullPointerException

Access by hierarchical idx %s failed: Encountered a null ele

Error message

Access by hierarchical idx %s failed: Encountered a null element by path %s.

What it means

extractValueByHierarchicalIndex throws NullPointerException when an intermediate (non-final) level of the path resolves to null. A null is only acceptable at the last level (returned as null value); a null before more levels remain means the nesting structure is shallower than the path demands.

Source

Thrown at grid/core-impl/src/datagrid/HierarchicalColumnsDataGridModel.java:445

    for (int i = 0; i < hierarchicalIdx.length; ++i) {
      int idx = hierarchicalIdx[i];
      if (idx < 0 || idx >= data.length) {
        throw new IndexOutOfBoundsException(
          String.format(
            "Access by hierarchical idx %s failed: Index out of bounds at element by path %s",
            Arrays.toString(hierarchicalIdx),
            Arrays.toString(Arrays.copyOfRange(hierarchicalIdx, 0, i))
          )
        );
      }

      result = data[idx];

      if (result == null && i == hierarchicalIdx.length - 1) {
        return null;
      }
      else if (result == null) {
        throw new NullPointerException(
          String.format(
            "Access by hierarchical idx %s failed: Encountered a null element by path %s.",
            Arrays.toString(hierarchicalIdx),
            Arrays.toString(Arrays.copyOfRange(hierarchicalIdx, 0, i))
          )
        );
      }

      if (result instanceof Object[] vals) {
        data = vals;
        continue;
      }

      if (result instanceof List<?> vals) {
        data = vals.toArray();
        continue;
      }

View on GitHub (pinned to be881553f2)

Solutions

1. Treat null intermediates as absent values: pre-check levels and short-circuit to null when a non-final level is null.
2. Make the data producer materialize empty arrays instead of nulls for missing intermediate levels.
3. Align column-hierarchy depth with the deepest row actually present, or prune columns for levels that never exist.

Example fix

// before
Object v = getValue(row, path); // throws NPE on null intermediate

// after
Object v = hasCompletePath(row, path) ? getValue(row, path) : null;

// helper
static boolean hasCompletePath(GridRow row, int[] path) {
  Object[] data = GridRow.getValues(row);
  for (int i = 0; i < path.length - 1; i++) {
    if (path[i] >= data.length) return false;
    Object o = data[path[i]];
    if (!(o instanceof Object[] a)) return false;
    data = a;
  }
  return true;
}

static boolean pathFullyMaterialized(Object[] values, int[] path) {
  Object[] data = values;
  for (int i = 0; i < path.length - 1; i++) {
    if (path[i] >= data.length) return false;
    Object o = data[path[i]];
    if (!(o instanceof Object[] a)) return false;
    data = a;
  }
  return true;
}
Object v = pathFullyMaterialized(GridRow.getValues(row), path) ? getValue(row, path) : null;

When it happens

Trigger: Path [0, 1, 2] where data[0][1] is null but the path expects one more level; rows whose nested sub-arrays are absent for optional columns.

Common situations: Sparse hierarchical data (optional nested sections serialized as null); a column hierarchy deeper than some rows' actual value nesting.

Related errors

• Row %d access failed: %s
• Access by hierarchical idx %s failed: Index out of bounds at
• Row %d failed: hierarchicalIdx cannot be null
• Row %d access failed: hierarchicalIdx cannot be empty
• Access by hierarchical idx %s failed: Encountered an unexpec

AI-assisted analysis of JetBrains/intellij-community@be881553f2 (2026-08-14). Data as JSON: /api/errors/c70812a58880c445. Report an issue: GitHub.