daimajia/AndroidViewAnimations · critical · Error

Can not init animatorClazz instance

Error message

Can not init animatorClazz instance

What it means

YoYo's Techniques enum entries each point to a Class object (animatorClazz) of a BaseViewAnimator subclass. getAnimator() reflectively instantiates it with Class.newInstance(); this Error is a catch-all rethrow of any failure during that reflective instantiation (no public no-arg constructor, wrong visibility, or an exception in the class's <clinit> or constructor). It is thrown as a hard java.lang.Error, not a RuntimeException, because at that point the library assumes its internal animation classes are well-formed.

Solutions

1. Do not obfuscate library animation classes: add ProGuard/R8 keep rules like -keep class com.daimajia.androidanimations.library.** { *; }
2. If you registered a custom Technique, make its animator class public with an explicit public no-arg constructor
3. Sync/upgrade the library version so animator classes match the Techniques enum entries (clean resolution: ./gradlew --refresh-dependencies)
4. Catch the Error at the call site and fall back to a safe animation (e.g. Techniques.FadeIn) or no animation
5. Reproduce with the reflective call wrapped in try/catch to log the original Exception 'e' — this error discards the root cause

Example fix

// before
public class MyAnimator extends BaseViewAnimator {
    private MyAnimator() {} // private ctor -> newInstance() fails
}
// after
public class MyAnimator extends BaseViewAnimator {
    public MyAnimator() {} // public no-arg ctor, required for reflection
}

// Sanity-check that the animator is reflectively instantiable before composing:
try {
    Object o = Techniques.FadeIn.getClass();
    // If you hold the animator Class yourself, verify:
    // Class<?> c = MyAnimator.class;
    // c.getDeclaredConstructor(); // throws if no no-arg ctor
} catch (Throwable t) {
    android.util.Log.w("YoYo", "Animator not instantiable", t);
}

// Java: verify the class hierarchy and modifiers before trusting a Technique's animator
static boolean isValidAnimator(Class<?> clazz) {
    return clazz != null
        && BaseViewAnimator.class.isAssignableFrom(clazz)
        && java.lang.reflect.Modifier.isPublic(clazz.getModifiers())
        && !java.lang.reflect.Modifier.isAbstract(clazz.getModifiers());
}

try {
    YoYo.with(Techniques.Bounce).duration(700).playOn(view);
} catch (Error e) { // getAnimator throws java.lang.Error
    Log.w("YoYo", "animation failed to init, skipping", e);
    // optional fallback:
    // YoYo.with(Techniques.FadeIn).duration(300).playOn(view);
}

When it happens

Trigger: Calling YoYo.with(Techniques.X) and letting it call getAnimator() when the resolved animator class cannot be reflectively instantiated: (1) the class has no public no-arg constructor, (2) the class is non-public/abstract or its constructor throws during animation setup, (3) the Class object does not actually extend BaseViewAnimator so the cast fails, (4) instantiation fails due to class-initializer errors (e.g. missing/renamed resources under a shrunk package).

Common situations: ProGuard/R8 obfuscation stripping or renaming animator subclasses so newInstance() fails at runtime; a forked/custom Technique added without a public no-arg constructor; library version changes that removed or renamed animator classes; animator static initialization throwing in certain device/theme environments.

Understand the failure class

Background: "This is a bug, please report it": internal invariant violations, unreachable panics, and SNH errors explained — this error's family across 47 libraries.

Related errors

• Can not be less than -1, -1 is infinite loop

AI-assisted analysis of daimajia/AndroidViewAnimations@6a35c466d2 (2026-09-08). Data as JSON: /api/errors/16d450c2ecc4d249. Report an issue: GitHub.

Appendix: source

Thrown at library/src/main/java/com/daimajia/androidanimations/library/Techniques.java:181

    ZoomOut(ZoomOutAnimator.class),
    ZoomOutDown(ZoomOutDownAnimator.class),
    ZoomOutLeft(ZoomOutLeftAnimator.class),
    ZoomOutRight(ZoomOutRightAnimator.class),
    ZoomOutUp(ZoomOutUpAnimator.class);



    private Class animatorClazz;

    private Techniques(Class clazz) {
        animatorClazz = clazz;
    }

    public BaseViewAnimator getAnimator() {
        try {
            return (BaseViewAnimator) animatorClazz.newInstance();
        } catch (Exception e) {
            throw new Error("Can not init animatorClazz instance");
        }
    }
}

View on GitHub (pinned to 6a35c466d2)