public void next(EntryListener listener) throws IOException {
        if (!hasNext()) {
            throw new IllegalStateException("no more entry");
        }
        int size = nextEntrySize;
        nextEntrySize = -1;
        listener.onEntry(buffer, size);
    }
Load data from file which stored in format: [size][data][size][data]....
indexr-common/src/main/java/io/indexr/util/ObjectLoader.java