Tencent/matrix · error · NoSuchFieldException

Method is not exists.

Error message

Method <fieldName> is not exists.

What it means

ReflectFiled.set() throws NoSuchFieldException with the (mis-worded) message "Method <fieldName> is not exists." when prepare() failed to resolve the requested field and ignoreFieldNoExist is false. It signals that the target class does not declare a field with the configured name.

Solutions

1. Correct the field name passed to the ReflectFiled constructor
2. Add ProGuard keep rules for the target class/field if obfuscation strips it
3. Pass ignoreFieldNoExist=true when the field is optional, then check the boolean return
4. Use setWithoutThrow() to swallow the miss and log instead of throwing
5. Verify the field exists via clazz.getDeclaredField(name) during development/debugging

Example fix

// before
ReflectFiled<String> f = new ReflectFiled<>(Foo.class, "namme");
f.set(instance, "x", false); // throws

// after
ReflectFiled<String> f = new ReflectFiled<>(Foo.class, "name");
boolean ok = f.set(instance, "x", true);
if (!ok) { MatrixLog.w(TAG, "field missing, skipped"); }

try {
    clazz.getDeclaredField(fieldName);
} catch (NoSuchFieldException e) {
    // field missing: fix the name or add keep rules before using set()
}

boolean fieldExists;
try { clazz.getDeclaredField(fieldName); fieldExists = true; }
catch (NoSuchFieldException e) { fieldExists = false; }

try {
    reflectFiled.set(instance, value, false);
} catch (NoSuchFieldException e) {
    Log.w(TAG, "field not found: " + reflectFiled.getFieldName(), e);
}

When it happens

Trigger: Calling set(instance, value, false) where mFieldName does not exist on the target class — wrong field name, field removed by ProGuard/R8 obfuscation, or field renamed between versions.

Common situations: Typo'd field names; reflecting on obfuscated classes without keep rules; library upgrades renaming private/internal fields; targeting the wrong class in a hierarchy (field declared only in a subclass/superclass).

Understand the failure class

Background: 'Could not be found', 'does not exist', 'not found in database': the resource-not-found family when an ID, slug, key, or URI lookup comes back empty — this error's family across 20 libraries.

Related errors

• Both of invoker and fieldName can not be null or nil.
• unable to cast object
• Both of invoker and fieldName can not be null or nil.
• Method is not exists.
• ---The Proguard mapping file 'mapping.txt' is not legal!

AI-assisted analysis of Tencent/matrix@3b8293bd65 (2026-09-08). Data as JSON: /api/errors/76bd9ea565989232. Report an issue: GitHub.

Appendix: source

Thrown at matrix/matrix-android/matrix-android-lib/src/main/java/com/tencent/matrix/util/ReflectFiled.java:127

        } catch (IllegalAccessException e) {
            MatrixLog.i(TAG, "getWithoutThrow, exception occur :%s", e);
        } catch (IllegalArgumentException e) {
            MatrixLog.i(TAG, "getWithoutThrow, exception occur :%s", e);
        }
        return fieldVal;
    }

    public synchronized boolean set(Object instance, Type val) throws NoSuchFieldException, IllegalAccessException,
            IllegalArgumentException {
        return set(instance, val, false);
    }

    public synchronized boolean set(Object instance, Type val, boolean ignoreFieldNoExist)
            throws NoSuchFieldException, IllegalAccessException, IllegalArgumentException {
        prepare();
        if (mField == null) {
            if (!ignoreFieldNoExist) {
                throw new NoSuchFieldException("Method " + mFieldName + " is not exists.");
            }
            MatrixLog.w(TAG, String.format("Field %s is no exists.", mFieldName));
            return false;
        }
        mField.set(instance, val);
        return true;
    }


    public synchronized boolean setWithoutThrow(Object instance, Type val) {
        boolean result = false;
        try {
            result = set(instance, val, true);
        } catch (NoSuchFieldException e) {
            MatrixLog.i(TAG, "setWithoutThrow, exception occur :%s", e);
        } catch (IllegalAccessException e) {
            MatrixLog.i(TAG, "setWithoutThrow, exception occur :%s", e);
        } catch (IllegalArgumentException e) {

View on GitHub (pinned to 3b8293bd65)