oracle/graal · error · IllegalArgumentException

Bad pattern: {}

Error message

Bad pattern: {}

What it means

Properties' pattern-based matcher (PropertyMatcher inner class) compiles the user-supplied value string with Pattern.compile(value, flags). If the string is not a valid java.util.regex, a PatternSyntaxException is caught and rethrown as IllegalArgumentException("Bad pattern: ...") so callers get one exception type for bad property-match specifications.

Source

Thrown at compiler/src/jdk.graal.compiler/src/jdk/graal/compiler/graphio/parsing/model/Properties.java:792

         * @param entireMatch whether the matcher should only accept full matches
         * @param flags flags to use to compile the pattern defined by {@code value}
         */
        public RegexpPropertyMatcher(String name, String value, boolean entireMatch, int flags) {
            if (name == null) {
                throw new IllegalArgumentException("Property name must not be null!");
            }

            if (value == null) {
                throw new IllegalArgumentException("Property value pattern must not be null!");
            }

            this.name = name;
            this.entireMatch = entireMatch;

            try {
                valuePattern = Pattern.compile(value, flags);
            } catch (PatternSyntaxException e) {
                throw new IllegalArgumentException("Bad pattern: " + value);
            }
        }

        @Override
        public String getName() {
            return name;
        }

        @Override
        public boolean match(Object p) {
            String s;
            if (p == null) {
                return false;
            }
            s = p.toString();
            Matcher m = valuePattern.matcher(s);
            return entireMatch ? m.matches() : m.find();
        }

View on GitHub (pinned to a66e9ccd1d)

Solutions

1. Fix the regex (balance groups/escapes); validate with Pattern.compile() in a try/catch before constructing the matcher
2. Use Pattern.quote(literal) when the value is meant to be an exact literal, not a regex
3. Pre-validate user-entered patterns in the UI and show the PatternSyntaxException message

Example fix

// before
new PropertyMatcher("name", "in(\d+", ...); // IllegalArgumentException: Bad pattern

// after
String val = java.util.regex.Pattern.quote(userInput); // literal match
new PropertyMatcher("name", val, ...);

static String validPatternOrThrow(String p) {
    try { java.util.regex.Pattern.compile(p); return p; }
    catch (java.util.regex.PatternSyntaxException e) { throw new IllegalArgumentException("Bad pattern: " + p, e); }
}

try { new PropertyMatcher(name, value, flags); } catch (IllegalArgumentException e) { /* surface PatternSyntaxException detail to the user, keep previous filter */ }

When it happens

Trigger: Constructing a PropertyMatcher (e.g. matching node or graph properties for filtering) with a malformed regex such as "in(\d+" (unbalanced group) or an invalid quantifier; the compile happens in the constructor, so it fails at matcher creation time, not at match time.

Common situations: User-typed filter expressions in a graph viewer (filter nodes by name/property); property rules copied from other tools that use a different regex dialect (e.g. Perl-only syntax like possessive or look-behind unsupported forms); unescaped user input used directly as a regex.

Related errors

• Property count is too big. Properties can contain only
• classForNode method shall return node class representation r
• Unknown type
• File header is missing
• Document properties unexpected in version < 7

AI-assisted analysis of oracle/graal@a66e9ccd1d (2026-08-14). Data as JSON: /api/errors/6af441c563669d93. Report an issue: GitHub.