Hoogerwerf (1970) wrote of chevrotains on Java occurring "from sea-level to high in the mountains". In the Dieng plateau area, V. Nijman (pers. comm. 2008) found them only a few times in the lowlands (400–700 m asl), where most survey took place, and had no records from above about 1,500 m asl. They have been found on Gunung Gede–Pangangro up to about 1,600 m asl (V. Nijman pers. comm. 2008). Hoogerwerf’s (1970) description of favoured habitats on Java suggests that chevrotains there might be an 'edge' species, certainly seeming to prefer areas with thick understorey vegetation, such as that along riverbanks. This would not be unusual within the genus (see other Tragulus accounts).

Tragulus javanicus as here defined is endemic to the island of Java, Indonesia, according to Meijaard and Groves (2004). The latter authors did not mention the island of Bali, but a sighting was reported from Bali Barat National Park, Bali, in a bird watching trip report (Birdquest 2006). The genus was not listed for Bali in the exhaustive reviews of Chasen (1940; of the genus) or Meijaard (2003; mammals of Indonesian islands), nor by Grubb (2005). Given the live-animal trade in the genus on Java, further records are needed to confirm whether or not there is a native population of the genus on Bali. If there is, biogeographic considerations suggest it would be most closely related to the Javan population and quite probably conspecific.

Hoogerwerf (1970) wrote that "in Java T. javanicus was encountered in all provinces, fairly intensively distributed from sea-level to high in the mountains". Present-day occurrence in East Java is questionable: S. Hedges, M. Tyson and E. Meijaard (pers. comm. 2008) know of no certain records (as distinct from listings in collation documents which do not cite information to primary source) from areas like Baluran or Alas Purwo national parks, despite high survey effort during 1991–2000.

Meijaard and Groves (2004) gave only one specific locality for the species: Cheribon (= Cirebon) on the north coast of West Java Province, which is the type locality of T. j. pelandoc Dobroruka, 1967. Dobroruka (1967) also mentioned the western part of Java, to the southern coast, for what he called T. j. focalinus (which is T. javanicus s .s.). Meijaard and Groves (2004) did not list the localities for the many specimens they examined. Dobroruka (1967) and Van Dort (1986) both discuss variation within Javan chevrotains; neither has yet been checked for specific localities. More recent localities, although not of specimen records, include: Gunung Halimun (reportedly camera-trapped some time before 2003 (Suyanto 2003), but the photograph is not reproduced in the appendix and a painting is used for the species instead); Ujung Kulon (1991–1993; van Schaik and Griffiths 1996, C.P. Groves pers. comm. 2008), and the Dieng Plateau (during 1999–2000; V. Nijman pers. comm. 2008). There has been no collation of records from the various surveys over the last 20 years or so, and some observers no doubt are aware of other localities.

Chevrotains on Java occur in some protected areas, e.g. Ujung Kulon (Hoogerwerf 1970; van Schaik and Griffiths 1996) and were earlier said to “occur in all game sanctuaries in Java and in most of the nature reserves established on that island...." (Hoogerwerf 1970). The species has been officially protected since 1931, yet it is still hunted.

The taxonomic revision of Meijaard and Groves (2004) means that T. javanicus is endemic to Java, and, if it occurs, Bali. There are fair indications of a decline, perhaps a major one, and thus this newly-revealed endemic species should be swiftly removed from the anonymity in which it has lain for decades. An urgent first step is a collation of existing information, because it is possible that many more records exist than were traced during the preparation of this assessment. This should include trawling likely observers and examination of collections not covered by Meijaard and Groves (2004). If insufficient number of specimens are found to clarify the number of taxa on Java, more should be obtained. Some may come from markets but, because of the pre-eminence of locality in determining systematics among very similar taxa, specimens of known locality origin must form the basis of analysis. Whatever the number of species on Java, the difference in sighting rate between Hoogerwerf (1970) and observers from the 1990s onwards is suggestive of a major decline, although other explanations are possible (see Population and Threats). Current status needs to be clarified through specific surveys for the genus (camera-trapping, but undertaken in a way more suitable for smaller species than is usual, spotlighting, and hunting surveys may all play a role). Surveys must take care to investigate secondary and edge areas which are often eschewed by general wildlife surveys in favour of the less encroached areas.