Please read the following table in Markdown format and then answer the question according to the table. Table cells in one row are seperated by '|', and different rows are seperated by '
'.

Table:
| District | Incumbent | Party | First elected | Result |
| --- | --- | --- | --- | --- |
| California 1 | Vacant | Vacant | Vacant | Democratic gain |
| California 2 | Marion Biggs | Democratic | 1886 | Retired Democratic hold |
| California 3 | Joseph McKenna | Republican | 1884 | Re-elected |
| California 4 | William W. Morrow | Republican | 1884 | Retired Republican hold |
| California 5 | Thomas J. Clunie | Democratic | 1888 | Lost re-election Republican gain |
| California 6 | William Vandever | Republican | 1886 | Retired Republican hold |
Question:
When was republican incumbent Joseph McKenna first elected?
Answer:
1884.0