apache/maven · error · IllegalArgumentException

if function requires exactly three arguments

Error message

if function requires exactly three arguments

What it means

if() (implemented as the method if_ in ConditionFunctions) is the ternary built-in of Maven 4.1 profile activation conditions (<activation><condition>). It throws IllegalArgumentException unless exactly three arguments (condition, valueIfTrue, valueIfFalse) are given; the activator reports 'Error parsing profile activation condition' and the profile does not activate.

Source

Thrown at impl/maven-impl/src/main/java/org/apache/maven/impl/model/profile/ConditionFunctions.java:185

     */
    public Object not(List<Object> args) {
        if (args.size() != 1) {
            throw new IllegalArgumentException("not function requires exactly one argument");
        }
        return !ConditionParser.toBoolean(args.get(0));
    }

    /**
     * Implements an if-then-else operation.
     *
     * @param args A list containing three arguments: condition, value if true, value if false
     * @return The second argument if the condition is true, the third argument otherwise
     * @throws IllegalArgumentException if the number of arguments is not exactly three
     */
    @SuppressWarnings("checkstyle:MethodName")
    public Object if_(List<Object> args) {
        if (args.size() != 3) {
            throw new IllegalArgumentException("if function requires exactly three arguments");
        }
        boolean condition = ConditionParser.toBoolean(args.get(0));
        return condition ? args.get(1) : args.get(2);
    }

    /**
     * Checks if a file or directory exists at the given path.
     *
     * @param args A list containing a single string argument representing the path
     * @return {@code true} if the file or directory exists, {@code false} otherwise
     * @throws IllegalArgumentException if the number of arguments is not exactly one
     * @throws ModelBuilderException if a problem occurs while walking the file system
     * @throws InterpolatorException if an error occurs during interpolation
     */
    public Object exists(List<Object> args) {
        if (args.size() != 1) {
            throw new IllegalArgumentException("exists function requires exactly one argument");
        }

View on GitHub (pinned to e4093d4e12)

Solutions

1. Always provide three arguments: if(contains(${os.name},'Linux'), 'unix', 'other')
2. Make sure the first argument evaluates to a boolean (comparison or boolean function)
3. Verify with mvn help:active-profiles after the fix

Example fix

<!-- before -->
<condition>if(contains(${os.name},'Linux'), 'unix') == 'unix'</condition>

<!-- after -->
<condition>if(contains(${os.name},'Linux'), 'unix', 'other') == 'unix'</condition>

static boolean arityOk(String condition, String fn, int min, int max) {
    int i = condition.indexOf(fn + "(");
    if (i < 0) return true;
    String args = condition.substring(i + fn.length() + 1, condition.indexOf(')', i));
    int n = args.isBlank() ? 0 : args.split(",", -1).length;
    return n >= min && n <= max;
}
boolean ok = arityOk(condition, "if", 3, 3);

try {
    Object r = new ConditionParser(functions, resolver).parse(condition);
} catch (IllegalArgumentException e) {
    // report and treat the profile as inactive
}

When it happens

Trigger: A condition like if(contains(${os.name},'Linux'), 'unix') missing the else branch — the parser requires all three arguments, e.g. if(cond, a, b).

Common situations: Dropping the else value while sketching; adding a fourth 'default' argument; forgetting that the condition argument must itself be a boolean expression, not a raw string.

Related errors

• length function requires exactly one argument
• upper function requires exactly one argument
• lower function requires exactly one argument
• substring function requires 2 or 3 arguments
• indexOf function requires exactly two arguments

AI-assisted analysis of apache/maven@e4093d4e12 (2026-08-21). Data as JSON: /api/errors/2ee90783b66bae58. Report an issue: GitHub.