Blankj/AndroidUtilCode · warning · UnsupportedOperationException

u can't instantiate me...

Error message

u can't instantiate me...

What it means

ActivityUtils (utilcode) is a final utility class whose private constructor throws UnsupportedOperationException. It exposes only static activity helpers; instances are intentionally forbidden.

Source

Thrown at lib/utilcode/src/main/java/com/blankj/utilcode/util/ActivityUtils.java:40

import androidx.annotation.AnimRes;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.core.app.ActivityOptionsCompat;
import androidx.core.util.Pair;
import androidx.fragment.app.Fragment;

/**
 * <pre>
 *     author: Blankj
 *     blog  : http://blankj.com
 *     time  : 2016/09/23
 *     desc  : utils about activity
 * </pre>
 */
public final class ActivityUtils {

    private ActivityUtils() {
        throw new UnsupportedOperationException("u can't instantiate me...");
    }

    /**
     * Add callbacks of activity lifecycle.
     *
     * @param callbacks The callbacks.
     */
    public static void addActivityLifecycleCallbacks(@Nullable final Utils.ActivityLifecycleCallbacks callbacks) {
        UtilsBridge.addActivityLifecycleCallbacks(callbacks);
    }

    /**
     * Add callbacks of activity lifecycle.
     *
     * @param activity  The activity.
     * @param callbacks The callbacks.
     */
    public static void addActivityLifecycleCallbacks(@Nullable final Activity activity,

View on GitHub (pinned to 7b4caf9e54)

Solutions

  1. Use the static API, e.g. ActivityUtils.startActivity(...), ActivityUtils.getActivityByContext(ctx); never instantiate.
  2. Configure reflective frameworks to skip final utility classes.
  3. Remove newInstance paths targeting ActivityUtils.

Example fix

// before
ActivityUtils a = reflectNew(ActivityUtils.class); // throws

// after
ActivityUtils.startActivity(intent);
Defensive patterns

Strategy: validation

Validate before calling

// ActivityUtils is static-only; never instantiate.
ActivityUtils.startActivity(intent);

Type guard

private static boolean isStaticUtility(Class<?> c) {
    return Modifier.isFinal(c.getModifiers()) && hasOnlyStaticMethods(c);
}

Prevention

When it happens

Trigger: Reflective instantiation or unsafe allocation of ActivityUtils rather than calling its static methods.

Common situations: Reflection/DI/serialization frameworks that build arbitrary classes; tests that reflectively scaffold utilities.

Related errors

AI-assisted analysis of Blankj/AndroidUtilCode@7b4caf9e54 (2026-08-14). Data as JSON: /api/errors/3ee616c7c7060b94. Report an issue: GitHub.