Wordorigins.org

These are a couple of slang terms for coffee. Java is the older of the two and the one with a known etymology. It is a reference to the island of Java in Indonesia, a place where coffee is grown. The term appears as early as 1823 in the pages of the Christian Spectator of 1 February of that year:

The most remarkable general characteristic of these works is their common relation to the Waverly Novels—a relation very much the same with that which ‘Roger’s Columbian Coffee’ bears to the real Java.