stanfordnlp/CoreNLP · error · IllegalArgumentException

Can't have null components!

Error message

Can't have null components!

What it means

AverageDataSeries stores every component to later average and compare domains; null components cannot be averaged. The constructor loops over the array and throws IllegalArgumentException as soon as it encounters a null element.

Solutions

1. Filter out null entries before constructing: use a List, add non-null series, then toArray.
2. Fix the producer code to omit null series instead of inserting null placeholders.
3. Validate the array with a null check loop before calling the constructor to give a clearer message.

Example fix

// before
DataSeries[] comps = new DataSeries[files.length]; // slots may stay null
AverageDataSeries avg = new AverageDataSeries(comps);
// after
List<DataSeries> comps = new ArrayList<>();
for (DataSeries s : maybeNull) if (s != null) comps.add(s);
AverageDataSeries avg = new AverageDataSeries(comps.toArray(new DataSeries[0]));

for (DataSeries s : components) {
  if (s == null) throw new IllegalArgumentException("Null component in series array");
}
AverageDataSeries avg = new AverageDataSeries(components);

boolean allNonNull(DataSeries[] arr) { return arr != null && java.util.Arrays.stream(arr).allMatch(java.util.Objects::nonNull); }

try {
  avg = new AverageDataSeries(components);
} catch (IllegalArgumentException e) {
  components = java.util.Arrays.stream(components).filter(java.util.Objects::nonNull).toArray(DataSeries[]::new);
  avg = components.length > 0 ? new AverageDataSeries(components) : null;
}

When it happens

Trigger: Calling `new AverageDataSeries(new DataSeries[]{seriesA, null, seriesC})` or passing an array produced by code that leaves null slots (e.g. pre-sized arrays partially filled).

Common situations: Arrays built with `new DataSeries[n]` and only some slots assigned, or optional data sources that returned null instead of skipping.

Related errors

• Need at least one component!
• Unknown position in AddDep operation
• Value cannot be both true and false.
• We need at least 2 extractors for ExtractorMerger to make…
• Argument " + i + " to class constructor is null

AI-assisted analysis of stanfordnlp/CoreNLP@1b7edd19c4 (2026-09-10). Data as JSON: /api/errors/229d30db0484739e. Report an issue: GitHub.

Appendix: source

Thrown at src/edu/stanford/nlp/stats/DataSeries.java:323

    }

  }


  // .......................................................................

  public static class AverageDataSeries implements DataSeries {

    private DataSeries[] components;

    public AverageDataSeries(DataSeries[] components) {
      if (components == null || components.length < 1)
        throw new IllegalArgumentException("Need at least one component!");
      this.components = new DataSeries[components.length];
      for (int i = 0; i < components.length; i++) {
        if (components[i] == null)
          throw new IllegalArgumentException("Can't have null components!");
        this.components[i] = components[i];
      }
      domain();                         // to ensure domains are same
    }

    public String name() {
      StringBuilder name = new StringBuilder();
      name.append("avg(");
      boolean flag = false;
      for (DataSeries series : components) {
        if (flag) name.append(", "); else flag = true;
        name.append(series.name());
      }
      name.append(")");
      return name.toString();
    }

    public double get(int i) {

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