Blankj/AndroidUtilCode · critical · NullPointerException

reflect failed.

Error message

reflect failed.

What it means

Utils.getApp() returns the cached Application (sApp); if it is null, it attempts to recover via UtilsBridge.getApplicationByReflect() and re-init. If after that sApp is still null, it throws NullPointerException("reflect failed."). This means the library was never initialized AND reflection could not locate the Application — a fatal, unrecoverable library state.

Source

Thrown at lib/utilcode/src/main/java/com/blankj/utilcode/util/Utils.java:72

            return;
        }
        if (sApp.equals(app)) return;
        UtilsBridge.unInit(sApp);
        sApp = app;
        UtilsBridge.init(sApp);
    }

    /**
     * Return the Application object.
     * <p>Main process get app by UtilsFileProvider,
     * and other process get app by reflect.</p>
     *
     * @return the Application object
     */
    public static Application getApp() {
        if (sApp != null) return sApp;
        init(UtilsBridge.getApplicationByReflect());
        if (sApp == null) throw new NullPointerException("reflect failed.");
        Log.i("Utils", UtilsBridge.getCurrentProcessName() + " reflect app success.");
        return sApp;
    }

    ///////////////////////////////////////////////////////////////////////////
    // interface
    ///////////////////////////////////////////////////////////////////////////

    public abstract static class Task<Result> extends ThreadUtils.SimpleTask<Result> {

        private Consumer<Result> mConsumer;

        public Task(final Consumer<Result> consumer) {
            mConsumer = consumer;
        }

        @Override
        public void onSuccess(Result result) {

View on GitHub (pinned to 7b4caf9e54)

Solutions

1. Call Utils.init(application) explicitly in your Application.onCreate() before using any util.
2. For unit tests on the JVM, use Robolectric or mock Utils.getApp() rather than relying on reflection.
3. Keep the library's UtilsFileProvider registered in the manifest so init happens automatically on cold start, or ensure your ContentProvider init does not race ahead of Application creation.
4. Add proguard/R8 keep rules for the Application class and the ActivityThread reflection path so getApplicationByReflect() succeeds in release builds.

Example fix

// before
// Application.onCreate does not init the library
int w = ScreenUtils.getScreenWidth(); // -> Utils.getApp() -> reflect failed.

// after
public class App extends Application {
  @Override public void onCreate() {
    super.onCreate();
    Utils.init(this);
  }
}

// Guard any code path that will call Utils.getApp().
public static Application requireApp() {
  Application app = Utils.getApp(); // will throw if reflect fails
  return app;
}
// Better: ensure init happened before first use.
if (Utils.getApp() == null) {
  // fallback only if you intentionally control init timing
}

try {
  Application app = Utils.getApp();
} catch (NullPointerException e) {
  // reflect failed: report init/r8/manifest problem; do NOT silently continue
  throw new IllegalStateException("AndroidUtilCode not initialized", e);
}

When it happens

Trigger: Calling any util that internally calls Utils.getApp() (e.g. ScreenUtils.getScreenWidth) before Utils.init() was invoked, in a context where reflection cannot find the Application (e.g. unit tests running on the JVM without an Android runtime, multi-process setups without UtilsFileProvider, or proguard/R8 stripping the Application class metadata).

Common situations: Running pure JUnit unit tests (no Robolectric/Android manifest) so reflection finds no ActivityThread.currentApplication(); forgetting Utils.init(this) in Application.onCreate; obfuscation stripping the ActivityThread access path; instantiating utils in a ContentProvider that runs before Application.onCreate on cold start.

Related errors

• u should init first
• u can't instantiate me...
• u can't instantiate me...
• ContentView is null.
• u can't instantiate me...

AI-assisted analysis of Blankj/AndroidUtilCode@7b4caf9e54 (2026-08-14). Data as JSON: /api/errors/d3e3f90a6a087979. Report an issue: GitHub.