Blankj/AndroidUtilCode · error · UnsupportedOperationException

u can't instantiate me...

Error message

u can't instantiate me...

What it means

NetworkUtils is a final utility class providing static methods for network detection (getNetworkType, getIPAddress, openWirelessSettings, etc.) and a NetworkType enum. Its private constructor throws UnsupportedOperationException to enforce static-only access.

Source

Thrown at lib/utilcode/src/main/java/com/blankj/utilcode/util/NetworkUtils.java:57

import static android.Manifest.permission.ACCESS_COARSE_LOCATION;
import static android.Manifest.permission.ACCESS_NETWORK_STATE;
import static android.Manifest.permission.ACCESS_WIFI_STATE;
import static android.Manifest.permission.CHANGE_WIFI_STATE;
import static android.Manifest.permission.INTERNET;
import static android.content.Context.WIFI_SERVICE;

/**
 * <pre>
 *     author: Blankj
 *     blog  : http://blankj.com
 *     time  : 2016/08/02
 *     desc  : utils about network
 * </pre>
 */
public final class NetworkUtils {

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

    public enum NetworkType {
        NETWORK_ETHERNET,
        NETWORK_WIFI,
        NETWORK_5G,
        NETWORK_4G,
        NETWORK_3G,
        NETWORK_2G,
        NETWORK_UNKNOWN,
        NETWORK_NO
    }

    /**
     * Open the settings of wireless.
     */
    public static void openWirelessSettings() {
        Utils.getApp().startActivity(

View on GitHub (pinned to 7b4caf9e54)

Solutions

  1. Use static methods: NetworkUtils.getNetworkType(), NetworkUtils.isWifiConnected(). Never instantiate.
  2. Access the NetworkType enum via NetworkUtils.NetworkType.NETWORK_WIFI etc.
  3. Exclude utility classes from DI scanning and serialization configs.
  4. Mock static methods with mockito-inline for testing.

Example fix

// before
NetworkUtils nu = new NetworkUtils();
boolean wifi = nu.isWifiConnected();

// after
boolean wifi = NetworkUtils.isWifiConnected();
Defensive patterns

Strategy: type-guard

Validate before calling

// NetworkUtils is static-only
NetworkUtils.NetworkType type = NetworkUtils.getNetworkType();
boolean wifi = NetworkUtils.isWifiConnected();

Type guard

static boolean isStaticUtility(Class<?> c) {
    return Modifier.isFinal(c.getModifiers()) && c.getSimpleName().endsWith("Utils");
}

Try / catch

try {
    NetworkUtils.class.getDeclaredConstructor().setAccessible(true);
    NetworkUtils.class.getDeclaredConstructor().newInstance();
} catch (UnsupportedOperationException e) {
    // Use static methods
}

Prevention

When it happens

Trigger: Direct or reflective instantiation by DI frameworks, mocking libraries, serialization frameworks, or manual reflection.

Common situations: DI component scanning of the utility package; Mockito mock creation targeting NetworkUtils; Gson/Jackson deserialization with the class as target; ProGuard keep rules that enable reflective construction.

Related errors

AI-assisted analysis of Blankj/AndroidUtilCode@7b4caf9e54 (2026-08-14). Data as JSON: /api/errors/45d4c42f16941521. Report an issue: GitHub.