Java has a unique position among Indonesian coffees. It is the original coffee planting area, with coffee coming to Batavia (Jakarta) and being planted in the area of Bandung early in the Dutch colonial era. The arabica coffee plant was brought to Indonesia from India in 1696. Java coffee had a legendary status around the world until the last century. Mocha and Java coffees commanded huge premiums, often 10x to 15x more expensive than Brazil coffees in brokers lists from the 1920s. Aside from history, Java is unique in that it is most often wet-processed, resulting in a relatively clean cup, without earthy or dirty flavors found in some lower-grade wet-hulled Indonesia coffees like Sumatra.
As far as the flavor profile, the coffee has moderate-to-low acidity; for a wet-processed coffee it can taste a little flat in that regard. It also tends to lack complexity, which can make a standard Java fall into the "blender" category more often than being spotlighted as a single-origin brew. These standard coffees are "Government Estate" Java, and they come from 4 old farms (Kayumas, Blawan, Djampit, Pancoer) that date back to Dutch colonialism. These farms are in the process of privatization, and in the past they were consistent, but rarely outstanding coffees.
These large farms are located in East Java in the vicinity of the Ijen volcanic complex. The Government body (called the PTP XXVI Plantation) grows about 85% of the coffee in East Java, close to Bali in the Ijen area. The range of altitudes suitable for coffee production is 3,000 to 6,000 feet with most growing in the plateau region at 4,500. Djampit and Blawan are the largest estates, while Pancoer is 1110 Hectares, and Kayumas is 725 Hectares. Blawan is huge: 2268 Hectares.
There is an old cultivar that can be found called Java Typica. But there is a lot of catimor-derived cultivars such as Kartika and Ateng. There's an older Typica type called "USDA", named after those who developed and endorsed it. But I have found old Typica coffee plants in the west of Java that could plausibly be from the original seedstock that came to Java from Yemen, with a stop in India. There is also Jember, which is named for the location of the coffee research center in East Java.
Most of what I see planted is Ateng type as well as some Timor variety, which both have robusta inputs. Timor is the natural arabica-robusta cross. The problem with Ateng is that once a farm or farmer can grow and process a coffee well, once there is no overlay of process flavors as you would find with wet-hull coffees, then you start to taste the cultivar more. And in the case of Ateng, this is not a good thing. It doesn't create outright bad coffee, as a processing defect or a black bean does, but there is a perceptible woody note or drying aspect in the aftertaste. For wet-hulled coffees, Ateng is fine, but for wet-processed, it's an issue.
We focus our efforts in Java Sunda, (West Java) although this is not the only place with the right factors to produce good coffee on the island. West Java was ignored as a source of quality coffee, but we find motivated farmers there, and an interest in smaller scale, quality-oriented coffee farming. The remaining issues are in training farmers in quality methods, care and attention to picking only ripe coffee cherry, and processing coffee well. The diverse farming efforts of small growers is admirable; they are often growing market crops like peppers, onions, beans and such. Those provide ready cash, and they look to coffee as a kind of annual "extra" income.
The problem with this is a lack of serious care for the coffee trees and for pruning and mulching organic inputs to keep the soil healthy. But the largest issues come from inter-planting coffee with other crops. Coffee should really only be planted with nitrogen-fixing legumes; even the shade trees should be leguminous. Other crops compete for limited nutrients and often for water as well. Coffee is often grown organically without pesticides or fungicides in Indonesia but the market crops are most certainly not! Sadly, they are intensively treated with fungicides, and the risk is that over-spraying or water contamination reaches the coffee. Coffee Berry Borer seems to not be as intense a problem in Java as it is in Sumatra.
We have taken quite a few trips to Java, and continue to do so, hoping to realize the potential of this historically important coffee origin, and to share a mutual benefit for both the farmers, with the increased prices we pay, and for us, a better cup of coffee to share with our customers.