microg/GmsCore · error · IllegalArgumentException

Not a long type

Error message

Not a long type

What it means

Flag.getLong() throws IllegalArgumentException("Not a long type") when the flag's dataType is not DATA_TYPE_LONG. The phenotype Flag class stores several differently-typed values (long, bool, double, string, bytes) and each typed getter validates the flag's type discriminator before returning the field. Calling a getter that does not match the flag's actual type is treated as a programming error and fails fast.

Source

Thrown at play-services-phenotype/src/main/java/com/google/android/gms/phenotype/Flag.java:71

    public Flag(String name, String stringValue, int flagType) {
        this.name = name;
        this.stringValue = stringValue;
        this.dataType = DATA_TYPE_STRING;
        this.flagType = flagType;
    }

    public Flag(String name, byte[] bytesValue, int flagType) {
        this.name = name;
        this.bytesValue = bytesValue;
        this.dataType = DATA_TYPE_BYTES;
        this.flagType = flagType;
    }

    public long getLong() {
        if (dataType == DATA_TYPE_LONG)
            return longValue;
        throw new IllegalArgumentException("Not a long type");
    }

    public boolean getBool() {
        if (dataType == DATA_TYPE_BOOL)
            return boolValue;
        throw new IllegalArgumentException("Not a boolean type");
    }

    public double getDouble() {
        if (dataType == DATA_TYPE_DOUBLE)
            return doubleValue;
        throw new IllegalArgumentException("Not a double type");
    }

    public String getString() {
        if (dataType == DATA_TYPE_STRING)
            return stringValue;
        throw new IllegalArgumentException("Not a String type");

View on GitHub (pinned to 157c9d86ac)

Solutions

1. Check flag.getDataType() (or flagType) before calling the getter and route to the matching getBool/getDouble/getString/getBytes
2. Add a switch/case over the DATA_TYPE_* constants that handles LONG and skips or defaults for other types
3. If the flag should always be long, verify the server-side experiment configuration hasn't changed the flag's type
4. Wrap the call in try-catch (IllegalArgumentException) only at boundaries where flag provenance is untrusted

Example fix

// before
long value = flag.getLong();
// after
long value = flag.getDataType() == Flag.DATA_TYPE_LONG ? flag.getLong() : 0L;

if (flag.getDataType() != Flag.DATA_TYPE_LONG) { throw new IllegalStateException("flag is not a long: " + flag.getDataType()); }

static boolean isLongFlag(Flag f) { return f != null && f.getDataType() == Flag.DATA_TYPE_LONG; }

try { long v = flag.getLong(); } catch (IllegalArgumentException e) { log.warn("Flag type mismatch", e); v = DEFAULT_LONG; }

When it happens

Trigger: Calling Flag.getLong() on a Flag whose dataType is DATA_TYPE_BOOL (2), DATA_TYPE_DOUBLE (3), DATA_TYPE_STRING (4), or DATA_TYPE_BYTES (5) instead of DATA_TYPE_LONG (1). Typically happens when iterating a heterogeneous list of Flags and blindly casting/calling getLong() on each.

Common situations: Iterating server-fetched phenotype flags without switching on flagType/dataType; a server experiment changed a flag's type from long to boolean; deserializing flags from a Bundle or proto where the type constant was set by another code path; copy-pasted getter calls across flag refactors.

Understand the failure class

Background: Type mismatch errors: IllegalArgumentException, TypeError and type guards across 150 open-source libraries — this error's family across 150 libraries.

Related errors

• Not a boolean type
• Not a double type
• Not a String type
• Not a bytes type
• remoteBinder is the wrong class.

AI-assisted analysis of microg/GmsCore@157c9d86ac (2026-09-06). Data as JSON: /api/errors/49d06e690ad3fd34. Report an issue: GitHub.