oracle/graal · error · UnsupportedOperationException

not implemented

Error message

not implemented

What it means

NodeList implements Collection<T> for API compatibility but deliberately leaves containsAll unimplemented because there is no efficient use for it on node input lists. Calling it throws UnsupportedOperationException('not implemented'), signalling an unsupported operation rather than a runtime fault. Other Collection methods like contains(Object) and addAll are implemented and should be used instead.

Source

Thrown at compiler/src/jdk.graal.compiler/src/jdk/graal/compiler/graph/NodeList.java:395

    @Override
    public int indexOf(Object node) {
        for (int i = 0; i < size; i++) {
            if (nodes[i] == node) {
                return i;
            }
        }
        return -1;
    }

    @Override
    public boolean contains(Object o) {
        return indexOf(o) != -1;
    }

    @Override
    public boolean containsAll(Collection<?> c) {
        throw new UnsupportedOperationException("not implemented");
    }

    @Override
    public boolean addAll(Collection<? extends T> c) {
        for (T e : c) {
            add(e);
        }
        return true;
    }

    @Override
    public String toString() {
        StringBuilder sb = new StringBuilder();
        sb.append('[');
        for (int i = 0; i < size; i++) {
            if (i != 0) {
                sb.append(", ");
            }

View on GitHub (pinned to a66e9ccd1d)

Solutions

1. Replace containsAll with an explicit loop over the other collection using contains(Object) or indexOf(o).
2. Copy the NodeList into an ArrayList before passing it to generic Collection APIs.
3. For set-like semantics, build a HashSet<Node> from the list and use standard set operations.

Example fix

// before
boolean hasAll = node.inputs().containsAll(required); // UnsupportedOperationException

// after
boolean hasAll = true;
for (Node r : required) {
    if (!node.inputs().contains(r)) { hasAll = false; break; }
}

static <T> boolean containsAll(NodeList<T> list, Collection<?> c) {
    for (Object o : c) {
        if (!list.contains(o)) return false;
    }
    return true;
}

static boolean isFullyImplementedCollection(Collection<?> c) {
    try {
        c.containsAll(java.util.List.of()); // cheap probe: empty containsAll still throws if unimplemented
        return true;
    } catch (UnsupportedOperationException e) {
        return false;
    }
}

When it happens

Trigger: Calling nodeList.containsAll(other) directly, or passing a NodeList into generic Collection machinery (e.g. Collection.retainAll, removeAll, or library code like Guava's Iterables/sets utilities) that invokes containsAll internally.

Common situations: Treating node.inputList() / usages as a plain Collection in helper code. Utilities such as Collections.checkedCollection, Set operations, or test assertions (assertEquals on collections) that probe with containsAll. Copying node lists into generic algorithms.

Related errors

• isEmpty() is not supported for performance reasons
• size() is not supported for performance reasons
• Graph was permanetly frozen.
• unknown verbosity:
• NodeBitMap was modified between the calls to hasNext() and n

AI-assisted analysis of oracle/graal@a66e9ccd1d (2026-08-14). Data as JSON: /api/errors/54de8d94fa3b02a5. Report an issue: GitHub.