stanfordnlp/CoreNLP · error · RuntimeException

Couldn't use swing to portray semantic graph

Error message

Couldn't use swing to portray semantic graph

What it means

convertTrees, when asked to visualize (-visualize option), reflectively loads edu.stanford.nlp.rte.gui.SemanticGraphVisualization, a Swing-based GUI class. If the class is missing (e.g. running a stripped/older jar or a headless environment where Swing initialization fails) or invocation fails, the underlying exception is wrapped in this RuntimeException.

Solutions

1. Run on a machine with a display and without java.awt.headless=true, and add the full CoreNLP jar (or model+gui packages) to the classpath.
2. Disable the visualize option and instead print trees with -conllx/-collapsed output when running headlessly.
3. Implement your own visualization (e.g. export to Graphviz DOT or use the web-based Stanford parser demo output) instead of the Swing viewer.

Example fix

// before
java -cp stanford-corenlp.jar edu.stanford.nlp.trees.GrammaticalStructureConversionUtils -visualize ...
// after
java -Djava.awt.headless=false -cp stanford-corenlp.jar:stanford-corenlp-models.jar:... \
  edu.stanford.nlp.trees.GrammaticalStructureConversionUtils ...
// or drop -visualize and use -outputFormat conllx

// Detect headless/unsupported env before enabling -visualize
boolean canVisualize = !GraphicsEnvironment.isHeadless()
  && Class.forName("edu.stanford.nlp.rte.gui.SemanticGraphVisualization", false, cl) != null;

try {
  convertTrees(args);
} catch (RuntimeException e) {
  if (e.getMessage() != null && e.getMessage().contains("swing to portray")) {
    log.warn("Visualization unavailable (headless or missing GUI classes); falling back to text output");
  } else throw e;
}

When it happens

Trigger: Running GrammaticalStructureConversionUtils.convertTrees with the visualize flag set on a classpath that does not contain the rte/gui visualization classes (often excluded from distributable jars), or in a headless environment (java.awt.headless=true, no X server/display) so Swing cannot initialize.

Common situations: Running on a server/CI without a display; using a minimal CoreNLP jar without the GUI packages; older Java versions or Wayland/X11 mismatch blocking AWT; the optional SemanticGraphVisualization class renamed/moved in a newer release.

Understand the failure class

Background: "X is not installed. Please install it with pip install Y": missing optional dependency errors — ImportError/ValueError raised when a library's optional extra was never installed — this error's family across 22 libraries.

Related errors

• Class at path
• Class is in classpath multiple times
• Could not create l1 minimizer! Reverting to l2.
• Could not load class at path:
• Could not load class in jar:

AI-assisted analysis of stanfordnlp/CoreNLP@1b7edd19c4 (2026-09-10). Data as JSON: /api/errors/0e6c37385dbf69b9. Report an issue: GitHub.

Appendix: source

Thrown at src/edu/stanford/nlp/trees/GrammaticalStructureConversionUtils.java:908

          // System.out.println("----------- CCprocessed dependencies -----------");

          if (generateOriginalDependencies) {
            printDependencies(gs, gs.typedDependenciesCCprocessed(GrammaticalStructure.Extras.MAXIMAL), tree, conllx, false, opts.convertToUPOS);
          } else {
            printDependencies(gs, gs.typedDependenciesEnhancedPlusPlus(), tree, conllx, false, opts.convertToUPOS);
          }
        }
      }

      if (portray) {
        try {
          // put up a window showing it
          Class sgu = Class.forName("edu.stanford.nlp.rte.gui.SemanticGraphVisualization");
          Method mRender = sgu.getDeclaredMethod("render", GrammaticalStructure.class, String.class);
          // the first arg is null because it's a static method....
          mRender.invoke(null, gs, "Collapsed, CC processed deps");
        } catch (Exception e) {
          throw new RuntimeException("Couldn't use swing to portray semantic graph", e);
        }
      }

    } // end for
  } // end convertTrees


  // todo [cdm 2013]: Take this out and make it a trees class: TreeIterableByParsing
  static class LazyLoadTreesByParsing implements Iterable<Tree> {

    final Reader reader;
    final String filename;
    final boolean tokenized;
    final String encoding;
    final Function<List<? extends HasWord>, Tree> lp;

    public LazyLoadTreesByParsing(String filename, String encoding, boolean tokenized, Function<List<? extends HasWord>, Tree> lp) {
      this.filename = filename;

View on GitHub (pinned to 1b7edd19c4)