Error creating map in MapDB: ClassCastException: [J cannot be cast to [B

Question

I am using MapDB, and attempting to create a direct-memory map, using long-arrays as keys, and I am getting the following error:

java.lang.ClassCastException: [J cannot be cast to [B
    at org.mapdb.Hasher$2.hashCode(Hasher.java:46)
    at org.mapdb.HTreeMap.hash(HTreeMap.java:954)
    at org.mapdb.HTreeMap.get(HTreeMap.java:390)

My code is:

Map<long[],LongBitsWrapper> inUseMap;

DB db = DBMaker
    .newMemoryDirectDB()
    .transactionDisable()
    .asyncWriteFlushDelay( 100 )
    .make();

HTreeMapMaker maker = 
    db.createHashMap( "longBitsInUseMap" )
        .hasher( Hasher.BYTE_ARRAY )
        .keySerializer( Serializer.BYTE_ARRAY );

inUseMap = maker.makeOrGet();

Any idea what I am doing wrong?

Answer 1

The map keys are of type long[] (binary name [J) but you're trying to use a hasher that works with byte[] ([B). Try using Hasher.LONG_ARRAY instead.