skylot/jadx · error · JadxRuntimeException

Classpath already loaded

Error message

Classpath already loaded

What it means

Thrown by ClspGraph.addClasspath() when nameMap is already non-null, meaning a classpath ClsSet has already been registered on this ClspGraph instance. The classpath can only be loaded once; subsequent calls are rejected to prevent duplicate or conflicting class data.

Source

Thrown at jadx-core/src/main/java/jadx/core/clsp/ClspGraph.java:53

	private final Set<String> missingClasses = new HashSet<>();

	public ClspGraph(RootNode rootNode) {
		this.root = rootNode;
	}

	public void loadClsSetFile() throws IOException, DecodeException {
		ClsSet set = new ClsSet(root);
		set.loadFromClstFile();
		addClasspath(set);
	}

	public void addClasspath(ClsSet set) {
		if (nameMap == null) {
			nameMap = new HashMap<>(set.getClassesCount());
			set.addToMap(nameMap);
		} else {
			throw new JadxRuntimeException("Classpath already loaded");
		}
	}

	public void addApp(List<ClassNode> classes) {
		if (nameMap == null) {
			nameMap = new HashMap<>(classes.size());
		}
		for (ClassNode cls : classes) {
			addClass(cls);
		}
	}

	public void initCache() {
		fillSuperTypesCache();
		fillImplementsCache();
	}

	public boolean isClsKnown(String fullName) {

View on GitHub (pinned to e738a26571)

Solutions

1. Create a new ClspGraph/RootNode instance for each independent classpath load.
2. Check whether nameMap is already populated before calling addClasspath() — guard the call with a null check.
3. Refactor the initialization flow to ensure loadClsSetFile() or addClasspath() is called exactly once per graph lifetime.

Example fix

// before
//   graph.addClasspath(set1);
//   graph.addClasspath(set2); // throws
// after
//   if (graph.getNameMap() == null) {
//       graph.addClasspath(set);
//   }

// Check before adding classpath
ClspGraph graph = root.getClspGraph();
// nameMap is private; use a guard method or ensure single initialization
// Safest: create a fresh RootNode for each independent classpath load
RootNode root = new RootNode(args);
root.getClspGraph().loadClsSetFile(); // call exactly once
// Do NOT call loadClsSetFile() or addClasspath() again on this root

try {
    graph.addClasspath(set);
} catch (JadxRuntimeException e) {
    if (e.getMessage().equals("Classpath already loaded")) {
        logger.warn("Classpath already loaded on this graph, skipping.");
        // Safe to ignore if the existing classpath is sufficient
    } else {
        throw e;
    }
}

When it happens

Trigger: Calling addClasspath() or loadClsSetFile() twice on the same ClspGraph instance. This commonly happens in code that re-initializes a RootNode or attempts to merge multiple classpath sets into one graph.

Common situations: Reusing a JadxDecompiler or RootNode instance across multiple decompilation runs without resetting the ClspGraph. Plugin or integration code that loads the classpath eagerly and then the core also loads it.

Related errors

• Unsupported Arg Type:
• String is too long:
• String read error
• No loaded files
• Failed to init res table provider: ${resTableParserProvider}

AI-assisted analysis of skylot/jadx@e738a26571 (2026-08-14). Data as JSON: /api/errors/c2703dedc596ba3c. Report an issue: GitHub.