pxb1988/dex2jar · error · DexWriteException

dup clz: " + name

Error message

dup clz: " + name

What it means

ConstPool.putClassDefItem() refuses to define the same class name twice; the pool already contains a ClassDefItem for the given type, so it throws DexWriteException('dup clz: <name>'). The dex format allows only one class_def entry per type.

Solutions

1. Deduplicate input classes before generation (keep one definition per class name)
2. Create a new DexFileWriter/Dex file for the second definition or skip already-added classes
3. Log and drop the second definition instead of adding it

Example fix

// before
for (Clz c : allClasses) writer.putClassDefItem(...);
// after
Set<String> seen = new HashSet<>();
for (Clz c : allClasses) { if (seen.add(c.name)) writer.putClassDefItem(...); }

if (poolContainsClass(name)) { skipOrMerge(name); } else { writer.putClassDefItem(access, name, superClz, itfs); }

try { writer.putClassDefItem(access, name, superClz, itfs); } catch (DexWriteException e) { if (String.valueOf(e.getMessage()).startsWith("dup clz:")) { /* skip duplicate */ return; } throw e; }

When it happens

Trigger: Calling putClassDefItem (directly or via DexFileWriter's class APIs) twice for the same class name within one DexFileWriter.

Common situations: Merging multiple class sources that both contain the same class; re-running a generation step against an existing DexFileWriter instance; duplicate class files on the input classpath (different casings resolved to same name).

Understand the failure class

Background: "already exists" / EEXIST / FileAlreadyExistsException: what the 'file already exists' error means and how to fix it — this error's family across 37 libraries.

Related errors

• Odex unsupported.
• Magic unsupported.
• Endian_tag unsupported
• Encountered RESTART_LOCAL on new v
• Invalid extended opcode encountered

AI-assisted analysis of pxb1988/dex2jar@b5bda4fb49 (2026-09-08). Data as JSON: /api/errors/add2389884904471. Report an issue: GitHub.

Appendix: source

Thrown at dex-writer/src/main/java/com/googlecode/d2j/dex/writer/item/ConstPool.java:223

    public AnnotationsDirectoryItem putAnnotationDirectoryItem() {
        AnnotationsDirectoryItem aDirectoryItem = new AnnotationsDirectoryItem();
        annotationsDirectoryItems.add(aDirectoryItem);
        return aDirectoryItem;
    }

    public AnnotationItem uniqAnnotationItem(AnnotationItem key) {
        AnnotationItem v = annotationItems.get(key);
        if (v == null) {
            annotationItems.put(key, key);
            return key;
        }
        return v;
    }

    public ClassDefItem putClassDefItem(int accessFlag, String name, String superClass, String[] itfClass) {
        TypeIdItem type = uniqType(name);
        if (classDefs.containsKey(type)) {
            throw new DexWriteException("dup clz: " + name);
        }
        ClassDefItem classDefItem = new ClassDefItem();
        classDefItem.accessFlags = accessFlag;
        classDefItem.clazz = type;
        if (superClass != null) {
            classDefItem.superclazz = uniqType(superClass);
        }
        if (itfClass != null && itfClass.length > 0) {
            classDefItem.interfaces = putTypeList(Arrays.asList(itfClass));
        }
        classDefs.put(type, classDefItem);
        return classDefItem;
    }

    public FieldIdItem uniqField(Field field) {
        return uniqField(field.getOwner(), field.getName(), field.getType());
    }

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