Blankj/AndroidUtilCode · info · UnsupportedOperationException

u can't instantiate me...

Error message

u can't instantiate me...

What it means

ImageUtils is a final utility class whose private constructor throws UnsupportedOperationException("u can't instantiate me..."). All image helpers (bitmap2Bytes, bytes2Bitmap, rotate, scale, round, save, etc.) are static; the constructor exists only to block instantiation, matching the library-wide *Utils convention.

Source

Thrown at lib/utilcode/src/main/java/com/blankj/utilcode/util/ImageUtils.java:70

import androidx.annotation.FloatRange;
import androidx.annotation.IntRange;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.annotation.RequiresApi;
import androidx.core.content.ContextCompat;

/**
 * <pre>
 *     author: Blankj
 *     blog  : http://blankj.com
 *     time  : 2016/08/12
 *     desc  : utils about image
 * </pre>
 */
public final class ImageUtils {

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

    /**
     * Bitmap to bytes.
     *
     * @param bitmap The bitmap.
     * @return bytes
     */
    public static byte[] bitmap2Bytes(final Bitmap bitmap) {
        return bitmap2Bytes(bitmap, CompressFormat.PNG, 100);
    }

    /**
     * Bitmap to bytes.
     *
     * @param bitmap  The bitmap.
     * @param format  The format of bitmap.
     * @param quality The quality.

View on GitHub (pinned to 7b4caf9e54)

Solutions

  1. Call the static API directly: ImageUtils.bitmap2Bytes(...), ImageUtils.rotate(...), ImageUtils.save(...), etc.
  2. Add ImageUtils to the exclusion list of any tool that reflectively instantiates classes.
  3. For a contract test, expect UnsupportedOperationException from the reflected constructor.

Example fix

// before (reflection)
ImageUtils iu = ImageUtils.class.getDeclaredConstructor().newInstance();

// after
byte[] png = ImageUtils.bitmap2Bytes(bitmap);
Defensive patterns

Strategy: validation

Validate before calling

// Never construct ImageUtils; it is static-only.
if (clazz == ImageUtils.class || Modifier.isFinal(clazz.getModifiers())) {
    // skip instantiation; use ImageUtils.xxx() statically
}

Type guard

if (clazz.getName().endsWith("Utils") && Modifier.isFinal(clazz.getModifiers())) {
    // static-only; do not newInstance()
}

Try / catch

try {
    Constructor<?> c = ImageUtils.class.getDeclaredConstructor();
    c.setAccessible(true);
    c.newInstance();
} catch (UnsupportedOperationException e) {
    // expected; use ImageUtils.xxx() instead
}

Prevention

When it happens

Trigger: Reflective instantiation via getDeclaredConstructor().newInstance() with setAccessible, or passing the Class to a reflective factory/coverage tool. A normal `new ImageUtils()` is a compile error because the constructor is private.

Common situations: Coverage/quality tools that instantiate every class; DI or reflective object mappers; a developer who expects instance methods; service loaders that scan packages.

Related errors

AI-assisted analysis of Blankj/AndroidUtilCode@7b4caf9e54 (2026-08-14). Data as JSON: /api/errors/eb15769539d864bb. Report an issue: GitHub.