Commits
Bryan Cutler authored and Micah Kornfield committed f3fde098b51
ARROW-1261: [Java] Add MapVector with reader and writer This adds `MapVector` as a subclass of `ListVector` where the data vector is a Struct with 2 fields: "key" and "value". A new writer `UnionMapWriter` is added that extends `UnionListWriter` to simplify writing key, value fields. Similarly, the `UnionMapReader` is added to read key, value fields. Author: Bryan Cutler <cutlerb@gmail.com> Closes #4444 from BryanCutler/java-map-type-ARROW-1279 and squashes the following commits: f53d11ed1 <Bryan Cutler> Added test to write data as list with different field names e68acd33f <Bryan Cutler> Expanded java docs for MapVector and UnionMapWriter 1b153e468 <Bryan Cutler> make StructVector respect nullable flag f627ed073 <Bryan Cutler> revert changes from using NonNullableStructVector 372764307 <Bryan Cutler> use Preconditions.checkArgument in MapVector 7f602b8fe <Bryan Cutler> Added split and transfer test afe89e29e <Bryan Cutler> fix style checks and add javadocs 03c380f6b <Bryan Cutler> fixed initializeChildrenFromFields in MapVector 3a9c19471 <Bryan Cutler> fix imports c90347e79 <Bryan Cutler> Now using StructVector with nullable false for struct and key vectors, writers can set a nullable flag to create non-nullable vectors 3e620d9c7 <Bryan Cutler> make MapVector use NonNullableStructVector e19f6cf27 <Bryan Cutler> Added roundtrip tests for MapVector Java IPC 4dcb622c8 <Bryan Cutler> initial MapVector with reader and writer