shwenzhang/AndResGuard · warning

UnsupportedOperationException

Error message

UnsupportedOperationException

What it means

ZipRODirectory is read-only; createDirLocal unconditionally throws UnsupportedOperationException. Any mutation path that reaches createDir on a ZipRODirectory (including createDir/getFileOutput in AbstractDirectory) fails because zip-backed trees cannot create new entries in place.

Solutions

1. Extract the zip into a real folder (new FileDirectory(unpackedDir)) and perform all mutations there.
2. Only use read APIs (getFileInput, containsFile, listEntries) on ZipRODirectory instances.
3. Wrap createDir in try-catch UnsupportedOperationException if your code must handle both read-only and writable directories.

Example fix

// before
Directory dir = new ZipRODirectory(apkFile, "");
Directory out = dir.createDir("new/res"); // UnsupportedOperationException
// after
File unpacked = new File("build/apk-unpacked");
unpacked.mkdirs();
Directory dir = new FileDirectory(unpacked);
Directory out = dir.createDir("new/res");

if (dir instanceof ZipRODirectory) { /* use read-only APIs or unpack to FileDirectory first */ }

boolean isWritableDirectory(AbstractDirectory d) { return d instanceof FileDirectory; }

try { return dir.createDir(path); } catch (UnsupportedOperationException e) { return unpackAndCreate(dir, path); }

When it happens

Trigger: Calling createDir(path) or getFileOutput on a ZipRODirectory obtained from an APK/zip, e.g. trying to add new resource folders directly inside the archive.

Common situations: Attempting to write obfuscated resources back into the source APK; copying a write-flow built on FileDirectory to a zip-backed Directory without changing types.

Understand the failure class

Background: UnsupportedOperationException and "is not supported" errors: when a library deliberately refuses a call — this error's family across 30 libraries.

Related errors

• DirectoryException

AI-assisted analysis of shwenzhang/AndResGuard@e4df245d82 (2026-09-12). Data as JSON: /api/errors/cf80baf0b7589e73. Report an issue: GitHub.

Appendix: source

Thrown at AndResGuard-core/src/main/java/com/tencent/mm/directory/ZipRODirectory.java:65

  public ZipRODirectory(File zipFile, String path) throws DirectoryException {
    super();
    try {
      mZipFile = new ZipFile(zipFile);
    } catch (IOException e) {
      throw new DirectoryException(e);
    }
    mPath = path;
  }

  public ZipRODirectory(ZipFile zipFile, String path) {
    super();
    mZipFile = zipFile;
    mPath = path;
  }

  @Override
  protected AbstractDirectory createDirLocal(String name) throws DirectoryException {
    throw new UnsupportedOperationException();
  }

  @Override
  protected InputStream getFileInputLocal(String name) throws DirectoryException {
    try {
      return getZipFile().getInputStream(new ZipEntry(getPath() + name));
    } catch (IOException e) {
      throw new PathNotExist(name, e);
    }
  }

  @Override
  protected OutputStream getFileOutputLocal(String name) throws DirectoryException {
    throw new UnsupportedOperationException();
  }

  @Override
  protected void loadDirs() {

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